My bet is on Day One games not being on any tier by the end of this year. It will be a similar approach to what PS+ is.
Difference being, Sony doesn't need a Gamepass to keep people on its platform, MS does. Without those AAA games Day One on GP, they'll lose what small userbase they have left, and very quickly.
Their cloud infrastructure is worse than what others like Sony and Nvidia already offer. Unless they dramatically improve that, then there is really nothing to keep people on the platform.
It'll be at that point we will see the final move over to software only publishing from MS. Everything else will be killed off. Including project Helix, which won't see past the R&D stage.