It'll be just like how the xbox one launched or new studios they'll be fine.
It's just that the Xbox One launched with games made by independent studios they no longer have relationships with. I just broke down the possibilities below and the majority of them seem like they failed. I bolded the candidates I think might be making launch games, and it's very few, as you can see.
Looking at the launch window lineup exclusives...
Forza 5 -> Fully expect a Motorsport or Horizon title at launch.
Killer Instinct -> I expect this one to get a new gen patch with a new season, definitely a good candidate.
Dead Rising 3 -> Capcom Vancouver has had a staff reduction after Dead Rising 4 didn't do too well, and that one was no longer a full exclusive. I could see another launch exclusive, but I find it somewhat unlikely as we already know it's Dead Rising 5.
Zoo Tycoon -> Wasn't highly rated, was followed up with Screamride which also wasn't highly rated. Now they make Jurrassic World and Elite Dangerous as self-published games, which are doing well. I doubt they're going to make another MS exclusive.
Fighter Within -> Ubisoft... only exclusive due to Kinect, unlikely to repeat.
Ryse: Son of Rome -> Crytek has been in trouble since then and doesn't have staff to make a AAA game. Considering how the relationship with MS went last time, I doubt this will be repeated
Crimson Dragon -> Doubt this will be repeated given how it turned out
Lococycle -> Studio is no longer with MS
Titanfall -> Respawn is making Titanfall 3 and Star Wars, Titanfall 2 wasn't exclusive, I doubt this will be repeated.
Sunset Overdrive -> First game did poorly while Ratchet did well and Spiderman will likely do well. I see Insomniac following up on both Ratchet and Spiderman, they won't have bandwidth to work with MS anytime soon.
Even factoring in later games...
Quantum Break -> Didn't do well, they're with another publisher now
Scalebound -> Relationship sounded disastrous, platinum is unlikely to come back
Reagent -> we'll see how Crackdown 3 does, but it doesn't have runaway success written all over it after the time it took to make it.
Creative Assembly's Halo Wars team -> Halo Wars 2 didn't do well, doubt this partnership gets renewed for that, and they're on Total War games now, which do well for Sega.
Meanwhile, their existing titles and rumored partnerships don't sound like they'll be ready at launch for the most part...
The Coalition's Gears 5 -> Might be ready for a 2020 launch, but that's if Gears 5 isn't an Xbox One project. I'm betting this one is a good candidate.
Playground's Fable is unlikely to be ready until 2021+ if it just started.
Splash Damage Gears -> Sounds like it's late this year or early next year, remains to be seen how it does, but it sounds like an Xbox One project.
Rare -> Incubating a new service game IP right now, and SOT took 4 years. Late 2021 seems like the earliest their next game could come.
343's Halo 7 -> Will take a while to reload if Halo 6 is an Xbox One project and comes out in late 2019.
Perfect Dark -> This one is a rumor, but I'm not sure who would be developing this. I can't think of a single large independent studio that's unaccounted for right now. If it's a Coalition / Splash Damage / Certain Affinity joint like I suspect, I could see it be a launch title, but again it remains to be seen how it does.