If your product incorporates any code licensed under GPL v3 your product has to be licensed under v3.
Once components of SUSE's Linux are under v3, and someone turns in a voucher, Microsoft automatically becomes a distributor of software under GPL v3.
Of course it may not matter. Some are predicting Microsoft will soon be standing side by side with the FOSS community seeking to ban software patents. They're constantly in court fighting patent infringement suits and it's already cost them far more than they could realize in revenue from licensing their own patents.