I can sum up this article:
1. Microsoft could sue Red Hat up the ass for IP infringement on (the article mentions OpenOffice). Then, when Red Hat can't pay up, offer a buyout. I call racketeering.
2. If that happens, or MS aquires RH in some other way, they could just dissolve all the engineers that RH has working on the major Open Source/Free projects (there's a lot of them). Apparently, they do enough work that Linux development would grind almost to a halt, especially in the more "boring" projects (like glibc). Note that I'm basing this note on statements made on Slashdot by a Red Hat programmer.