The problem I think would be the impression that some users get just by the fact that such a feature exists. To some, it creates a negative impression if their new device has a feature which the cannot utilize - it would almost be better (for marketing purposes) if the feature didn't exist at all. If you're trying to use game streaming as a feature to help sell the console, that is not going to work well for selling to all the people with AMD graphics card, and just might have the opposite effect. (E.g. "Why would I buy a Switch? I can't even use the game streaming and I'm not planning on buying a new graphics card.")
Maybe this is something they could add down the line, and I hope they do... But I think it could create some complications with their image upon release, so again, I'm not counting on it. Either way, it would need to be marketed as a "bonus" feature and not as a major selling-point to prevent misconceptions some might get about it.