They will try to scare a few companies into giving them protection money, but as a convicted abusive monopolist they have to watch their step even there - they could easily be sued for casting a cloud over someone else's business.
Meanwhile SCO has caused the FOSS community to hone it's claws. Microsoft says they can't reveal the patents because FOSS would retaliate - in other words they are fully aware their patents don't stand a chance if challenged.
A system is prepared to find prior art and another system with counter-patents. Groklaw will expose every attempted deception to the light of day.
And the Supreme Court has just pulled the rug out from under "trivial" patents.
And should things get tight for Linux, waiting in the wings is a very large blue company that has a lot bet on Linux. This large blue company has a "significant" team of very polite, very patient, but very persistent and insanely competent lawyers, popularly known as the Nazgul.
And more patents than God.
I do not doubt that Microsoft's lawyers have nightmares about this large blue company pulling out a patent covering "Using a computer to write software programs".