What borrowing money? Microsoft has enough cash to buy another ABK again this year. The problem is that Satya and the other ghouls at Microsoft's council are tired of Xbox failing to deliver for over a decade now. ABK was supposed to be a turning point and it failed again. Microsoft can't pull any exclusive stunt because it would erode into Xbox's financials even further and Satya's bonuses are tied even tighter to Xbox's results this year probably in response to it being neglected forever now. The only way out is progressively going full third party.
Now the one playing 4D chess here is Gaben. When Microsoft was doing the rounds offering CoD assurance contracts Valve was the only one that didn't sign and said it publicly that they "trust Microsoft" making it harder for any of these exclusive initiatives to happen. Valve already had the PC gamer mindshare and Microsoft can't do anything about it without triggering even more bad faith against them.
Big companies don't use their cash for these things, at least not entirely, instead use leverage (or in other words debt) to be able to reduce your risks and get additional cash flow for cheap. This way you can continue to invest your cash while you complete your transactions.
These companies are also known to issue bonds as well, but I don't understand that game as much.
Notice how when interest rates began to drop, you got Phil talking about maybe making more acquisitions again.. Again, these things are correlated.
Also yes, I acknowledge that doing exclusivity moves are a risk. But Microsoft has IPs that are very, VERY valuable to the PC gamers and likely cannot be mass-ignored like what happened with the EGS timed exclusives. Alternative launchers have proven their success if the games are popular.
What I'm saying is, MS does have tools at its disposal than any past foe of Valve's. Does that guarantee success? No, nothing is guaranteed in this life.
But I do think we will see Valve have to adapt to it.