The reason why so much effort is being poured into maintaining the charade is because theres a 10-20m userbase of very diehard users who all have an absurdly high likely hood of maintaining their higher tiers of GP subscriptions through this.
They wanna maintain that revenue stream as long as possible while they, over-time, restructure Xbox into a far leaner endeavor that focuses on a handful of mega-projects.
These cuts are gonna go on for a much longer while, and the sad part is - if the gaming community finally said 'enough is enough' and just all chose to divest, and tbh its hard to argue we're not already there given how returns have been (outside of ABK) the last couple of years - Microsoft would just expedite the process and close off even more teams now. To them, whether someone like 343, now Halo Studios, makes Halo versus just outsourcing it out is just semantics to them, plus Halo hasn't been 'Halo' since Bungie bought their way out.
MS is never gonna have the come to Jesus moment that media mouth pieces keep claiming just around the corner for team Xbox.