It would be fine, but as long as future models are upgradable (and upgrade is easy/simple like the N64 RAM upgrade was).
It's not like your old Xbox would stop working. Even in the PC world this is not how it works.
I built my PC *FIVE* years ago with a Nvidia GTX 570 GPU, which was wasn't even the top of the line GPU of that time (more like upper mid-range, the 580 was higher end) ... and today that GPU can still run new games like Street Fighter V and it can run The Witcher 3 at 1080P at medium settings. Totally playable.
https://www.youtube.com/watch?v=4ORVwS377Ck
It can run Star Wars Battlefront at 1080P 60 fps too:
https://www.youtube.com/watch?v=NugPmeBzXAI
People need to get over their fear that upgradable hardware = your older hardware is instantly useless.