If they leave consoles they will definitely try and buy Valve and then EA or Take2.They'll probably try to buy Valve tho, but i'm sure Gabe Newell will tell them to go f*ck themselfs
Im not sure Gabe will say no, he has a soft spot for them and probably will bank in 100+ billion sale.
I always had a feeling it will come to it at the end, especially if MS want to stay relevant in video games one way or another, its there best chance.