If this goes through, I wonder what would happen to Skype's Linux and Mac support. I'd hope MS would still support it, but I don't think they have any Linux software currently (I'm not positive about that, so please correct me if I'm wrong) and the Mac version of Office is always delayed compared to the Windows version. I hope Skype doesn't similarly languish.
1. Linux/Mac users would move because they had to.
2. Linux/Mac users that use Skype to communicate with long-distance friends and family would convince them to jump ship to another platform (if only to be able to do video conferencing).
3. People pissed off at MS would migrate on principle (though maybe only if there was a viable alternative to the way they currently use Skype).