Bullies tend to pick victims who can't fight back too effectively, so I doubt they'd go after Microsoft.

All the big tech companies have a bunch of vague patents than in a just world would never exist, and they seldom go after each other, because they know then they'll be hit with a counter-suit alleging they violate multiple patents too, and in the end everyone except the lawyers will be worse off. It's sort of like mutually assured destruction. They don't generally preemptively invalidate each other's patents, so if Microsoft is not a party to the suit, they'll likely stay out of it entirely.

However, newer and smaller companies are less likely to be able to counter-sue as effectively, so if they pose a threat of taking revenue from the big companies (e.g. by launching on competitor platforms only), they are ripe targets for patent-based harassment.