Would it be possible for Pokemon to retire the concept of “fainting”? Originally, Game Freak wasn’t even sure what fainting even meant–when you tried to send out a fainted Pokemon it said “there’s no will left to fight,” and in the early anime trainers simply withdrew a Pokemon when it clearly couldn’t fight anymore. So what if “[Pokemon] fainted” could be replaced with “[Pokemon] gave in” or something?

I’m not sure that it matters, particularly?  I certainly wouldn’t have a problem with changing it, but “fainted” isn’t a terrible word for what they use it to mean, and the condition itself is simple enough – the Pokémon can’t battle, full stop – that I don’t think it’s all that important to have precise language for describing it.  You could do away with the entire concept, and replace it with a range of more specific ways a Pokémon can be debilitated, each caused by particular attack types, requiring specialised forms of care and having different lingering effects after the Pokémon is healed.  I think you could build an interesting system out of that, although it wouldn’t be a very good fit with Pokémon’s general direction over the last several generations; it’s more of a “darker and grittier” mechanic.  If it’s just changing the name to slightly better reflect what we already imagine is happening, I could happily go either way.