Rocket League is the only third-party game anyone really needs, but obviously it's not the only one Switch is getting. More than that though, you claim that the 3DS and Gamecube had game libraries "on life support," which is obviously talking out your ass. People constantly request GCN remakes for the new gen, it was a huge cult smash, especially among Smash players. The 3DS library is far larger than the PS4 library. Guess Sony is on life support. /s
3DS was not life support, but it was not them at their finest. I have said before in similar discussions how when I was doing a retrospective series involving a lot of DS games (them tending to be ones I really liked playing or at least having something interesting to showcase) I would do a "where are they now?" bit. So many of them had vanished for the 3ds and were doing android and IOS stuff, and anything they did do for the 3ds was mirrored and probably better on other platforms. Maybe it was enough for some people (by and large I don't really care for most Nintendo properties which could make me something of an outlier) but it did not have what made the GBA and DS great, and sees me play them to this day.
People constantly request remakes of everything, I tend not to pay them much attention, especially smash players given the farce that whole scene became (competitive smash is so shockingly poorly implemented I tend to use it as a case study of how not to, though I suppose I can say compared to other versions the GC version was probably the most coherent).
If you reckon the GC library was good enough then congrats on having lower standards than me I guess, much like not being one able to drink 20 pints and still be able to walk home makes for cheap night out it is not an unenviable position but I have been spoiled (at the time by the PS2 and later on the xbox for certain things). That probably handles rocket league as well -- as a competitive game it is not without merit but there is way more to games than that for me. I liked my GCs, had a great time with several games even (then and to this day) and it was not as embarrassing for Nintendo as the N64 or Wii U (we will leave the Wii for now but suffice it to say I don't look favourably upon its library either, and if you want to talk release droughts then settle down as we are in for a long one, or perhaps not as a drought is an absence of things). Had I wanted to experience a good slice of games and gameplay styles (though we might have to break it down between PC and consoles as they were still doing different things at the time) at the time though I would have been out of luck. Going further I would have to ponder whether the requests for remakes might be because nobody had one at the time and a remake represents a better chance to play one (to say nothing of hopefully benefiting from the refinement the last 10-15 years of game design have brought) -- something like eternal darkness (reviewed well at the time, sold enough that it can hardly be said to have been missed at the time...) would set you back a reasonable chunk of change going by Amazon prices right now.
If you reckon the PS4 and 3ds are valid things to compare then so be it. Had a look on the numbers vs the DS if that matters? The ps4bone is at risk of seriously underwhelming me though, actually in a similar way that the 3ds did coming off the GBA and DS. I don't think I am getting old and if I am it is playing out vastly differently to how I see the same where people are stuck liking the music from when they were 19.
It is more that when I look at the NES, SNES, GB-GBA and DS that a majority of the awesome games for them, be them my picks or those in every top ?? list I have ever read, feature third party games everywhere*. When people then turn around and say Nintendo only needs Nintendo (and its stable) that I have to question what they are smoking. The various presentations were a bit better than I expected but not close to the levels I needed to start feeling any enthusiasm. The responses to it seemed a bit uneasy and then in what almost seemed like tones used by religious apologetics we got "but now it is portable" (as much as the switch can be considered as such).
*I recall a thread around here once that asked about the state of cartoon network and how it was better "back in the day". I then had to question when the day was for looking at ages such a thing would have been when I thought they had lost it. It is not then impossible that someone grew up thinking the N64 and GC were Nintendo doing some kind of well.
Going further I have previously stated I hate the console model and want everybody to go the DVD route where I can buy one of a thousand different models with varying specs but, give or take the horrors of region locking, they all work with my DVD I got from the shop though. Were I someone else I might say I hope Nintendo prove me wrong but I do actually hope Nintendo get driven into the ground, they get no amiibo sustenance type bubble and they reinvent themselves as a third party company.