The recent acquisition surely with gamepass in mind. Even jason schreicer mentioned same on his twitter that microsoft aim to quadrable their current subs.Prior to the acquistion, they owned several large scale AAA developers that they built. Then, in 2018, they purchased several smaller studios with the aim to grow them. Now, they've purchased a raft of established studios. It sounds to me that Microsoft are covering their bases; small scale, medium scale, and large scale games. Then there's The Initiative - described as the first AAAA studio. Microsoft built that from scratch, so who knows what they're cooking up.
from what i see, since their current first party studio take time to release game, with Halo Infinite fiasco that get delayed next year or possibly delayed again for another 2022, there no other game to cover for it. The recent acquisition is probably to cover the empty gap while their own studio 'ready' to finish and ship their game. Atleast for now, the "xbox has no game" problem been 'fixed' for awhile. So after this i expect their 1st party/smaller studio and established studio that they buy will take turn covering the gap in market period window to make sure games are keep pumping in for the gamepass.