MS can now buy anything and anyone they want
After this gets approved with the purposed Remedies, the odds of them buying another publisher is close to off the table at this point. If they try to buy Sega or someone small, they are going to get raked through the coals.
And I know from people I talk to who have Microsoft investments, that a lot of big players on the board are not super happy right now with Xbox division. The odds of them in a year or so going after another publisher would automatically be blocked.
They can buy studios, but even then the size of them would be looked at from this point on.