They confirmed already that the game is for this generation of consoles. We might not even have another next gen. You might not be wrong but its really hard to even guess at that when we don't have a release date on the next generation if it even exists in the same way we've been upgrading. They could just keep inching forward like with scorpio
True, I don't expect the OG Xbox One to be able to play Halo infinite though, and even if it does, it'll be a significantly handicapped version of the game. The difference between the way an OG XB1 and a Xbox One X can play a game like Assassins Creed Origins (A game that is almost a year old now) is pretty drastic. Games that come out in the 2019-2020 range probably won't be possible on the older hardware.