Thing is Sony and Nintendo have been able to find success outside of major franchises and create new ones. Microsoft has yet to do that.
So unless they approach those current franchises with being able to completely, re-work everything and create something special like Zelda:BOTW, for Sony Uncharted 4, God of war even though it's not out people can't stop talking about it, even Mario is being talked a shit ton because of how batshit nuts it looks. I don't see Gears and halo making those kinds of waves,especially after master chief collection and halo 5 campaign, gears 4 as well though mechanically sound has a been there done that feel with nothing really new that excites you.
Nintendo has done so with Splatoon, but I doubt the budget of Splatoon is up to AAA standards. Sony has been able to build new franchises due to the way they're set up, and because their success has allowed them to luxury to take risks. Microsoft does need to make sure its pillar franchises are healthy before heading into unknown territory. I always see people asking for new IPs from them, but I always thought what must be done is to make people CARE about Halo and Gears again.
With any franchise, in games or otherwise, there's a certain point where you have to innovate and offer "hooks". That point is usually when the perception of quality stops growing from one installment to the next. Halo 2 didn't really reinvent the wheel, but the perception of quality grew from 1 to 2 in the overall market. Same going from 2 to 3. After that, the perception of quality didn't immediately decline, but it plateaued. Reach wasn't seen as meaningfully better than 3, and 4 was actually seen as a decline from 3. By that point, you're already past the moment where you should think of having a strong hook to reinvigorate the series. I think 343 recognized it, and tried to have a story hook with the introduction of Locke, and a multiplayer hook with Warzone, free DLC, and an e-sports focus.
Gears 4 didn't really have an obvious hook. Hard to grasp what they were going for with that one, but they might have thought that the generational transition was a strong enough pull.
I think these hooks weren't at all strong enough. They need something far more drastic next time around. Without that, I truly, honestly see the possibility of devastating outcomes for Xbox as a whole. I don't think they have many other options for renewed relevance and future growth, barring a surprise hit.