So I've been thinking this over and I'm really not sure what the drawbacks would be, if any even exist, to the idea, I can think of only one that I'll address, that ultimately wouldn't matter to the parties involved.
Sony and Microsoft are seemingly done with the portable market, there has been no follow up to the Vita, and while there was never a portable Xbox, Microsoft doesn't even seem to make their own smartphones anymore (unless I'm missing something). Meanwhile, Nintendo has a great portable gaming device of their own in 2 current models, that could easily make for a vessel to remote play your own PlayStation and/or Xbox system. Much in the same way you could remote play a PS4 with a Vita, except the Switch has enough buttons to properly map 1 to 1 with a PlayStation or Xbox controller. Granted, the triggers are not analog, but you can still get by without that all the same.
We know both Sony and Microsoft must be interested in this prospect to some extent. About a year ago, Sony surveyed some PS4 owners and asked specifically (among many other things) if they'd welcome the ability to remote play their PlayStation with a Nintendo Switch (named specifically among other non-Sony handheld devices). Meanwhile, MIcrosoft has put Xcloud and Gamepass on smartphones (among other devices) to allow players to experience Xbox games on the go; of course most smartphones lack proper built in physical controls, so this solution kinda pales in comparison to what a Switch brings to the table in terms of a more pleasant closer to the real feel portable gaming experience.
We know the Switch is capable, the homebrew scene has found ways to remote play your PC on the Switch, and through a little more effort to unofficially remote play a PS4 on the Switch. The biggest barrier (beyond owning both devices) will be the strength of your internet, especially for the portable Switch, but we're just entering the 5G era, and our smartphones can all easily be made into mobile hotspots, granted while we may have unlimited data these days, we may not yet have unlimited 5G hotspot data and for most plans that may downgrade to 4G hotspot data at a certain point; but that will only improve with time, remote play should only become all the more fluid as technology advances, thanks to the simple nature of any smartphone being capable of turning into a mobile hotspot while the data speeds the phones receive only continue to increase with time.
So why wouldn't Nintendo want this? It would realistically lead to more Switchs sold to Xbox and PlayStation owners that don't already own the device, who are looking for a great way to remote play their systems on the go. And why wouldn't Microsoft or Sony want this? It would probably lead to some Switch owners buying an Xbox or Playstation just because they want even more great games to be playable on their hybrid device. And none of them gets cheated here, you have to own both a Switch and an Xbox or Playstation, to experience the games of both devices, this isn't some sneaky way to get games from another device on one system without owning the other system.
The only people that might object to this as mentioned earlier, would be third party devs who love when a player enjoys a game so much that they buy it again for another system, just for say the ability to now play it on the go such as Rocket League, Doom, or Skyrim. Thing is, third party devs have no say in the matter, they may object, but they can't stop Nintendo, Sony, or Microsoft from making such a joint venture. Now, perhaps Microsoft would object because they benefit from the likes of Minecraft being sold multiple times to the same people so they can experience it on all their systems of choice. I'm sure that's probably a sizable amount of money honestly, but Minecraft would still undeniably be a huge success even if they pulled this kind of move. But if Microsoft didn't object purely for Minecraft and/or any other Xbox games that they also sell on the Switch like Cuphead, then they could simply make those games not be accessible when remote playing your Xbox on the Switch; that would be a little scummy, but it's a small selection of games that it would affect, so it wouldn't be the biggest of deals.
I really really want to see such a thing happen, and to some small extent it all seems and feels so feasible and like it might even happen, yet on the other hand, I know absolutely better than to hope for such a game-changing feature, even if I still strongly believe it could greatly benefit each party that would be involved with making such a thing a reality.
Sony and Microsoft are seemingly done with the portable market, there has been no follow up to the Vita, and while there was never a portable Xbox, Microsoft doesn't even seem to make their own smartphones anymore (unless I'm missing something). Meanwhile, Nintendo has a great portable gaming device of their own in 2 current models, that could easily make for a vessel to remote play your own PlayStation and/or Xbox system. Much in the same way you could remote play a PS4 with a Vita, except the Switch has enough buttons to properly map 1 to 1 with a PlayStation or Xbox controller. Granted, the triggers are not analog, but you can still get by without that all the same.
We know both Sony and Microsoft must be interested in this prospect to some extent. About a year ago, Sony surveyed some PS4 owners and asked specifically (among many other things) if they'd welcome the ability to remote play their PlayStation with a Nintendo Switch (named specifically among other non-Sony handheld devices). Meanwhile, MIcrosoft has put Xcloud and Gamepass on smartphones (among other devices) to allow players to experience Xbox games on the go; of course most smartphones lack proper built in physical controls, so this solution kinda pales in comparison to what a Switch brings to the table in terms of a more pleasant closer to the real feel portable gaming experience.
We know the Switch is capable, the homebrew scene has found ways to remote play your PC on the Switch, and through a little more effort to unofficially remote play a PS4 on the Switch. The biggest barrier (beyond owning both devices) will be the strength of your internet, especially for the portable Switch, but we're just entering the 5G era, and our smartphones can all easily be made into mobile hotspots, granted while we may have unlimited data these days, we may not yet have unlimited 5G hotspot data and for most plans that may downgrade to 4G hotspot data at a certain point; but that will only improve with time, remote play should only become all the more fluid as technology advances, thanks to the simple nature of any smartphone being capable of turning into a mobile hotspot while the data speeds the phones receive only continue to increase with time.
So why wouldn't Nintendo want this? It would realistically lead to more Switchs sold to Xbox and PlayStation owners that don't already own the device, who are looking for a great way to remote play their systems on the go. And why wouldn't Microsoft or Sony want this? It would probably lead to some Switch owners buying an Xbox or Playstation just because they want even more great games to be playable on their hybrid device. And none of them gets cheated here, you have to own both a Switch and an Xbox or Playstation, to experience the games of both devices, this isn't some sneaky way to get games from another device on one system without owning the other system.
The only people that might object to this as mentioned earlier, would be third party devs who love when a player enjoys a game so much that they buy it again for another system, just for say the ability to now play it on the go such as Rocket League, Doom, or Skyrim. Thing is, third party devs have no say in the matter, they may object, but they can't stop Nintendo, Sony, or Microsoft from making such a joint venture. Now, perhaps Microsoft would object because they benefit from the likes of Minecraft being sold multiple times to the same people so they can experience it on all their systems of choice. I'm sure that's probably a sizable amount of money honestly, but Minecraft would still undeniably be a huge success even if they pulled this kind of move. But if Microsoft didn't object purely for Minecraft and/or any other Xbox games that they also sell on the Switch like Cuphead, then they could simply make those games not be accessible when remote playing your Xbox on the Switch; that would be a little scummy, but it's a small selection of games that it would affect, so it wouldn't be the biggest of deals.
I really really want to see such a thing happen, and to some small extent it all seems and feels so feasible and like it might even happen, yet on the other hand, I know absolutely better than to hope for such a game-changing feature, even if I still strongly believe it could greatly benefit each party that would be involved with making such a thing a reality.