Microsoft is all about building up it's mobile patent portfolio soooo buying Nokia and RIM/Blackberry would be huge giant steps in the dirrection they want.
R8 now im dreaming a situation ie after buying bb ms bring a surface phone in market which is capable of dual booting windows and bb10 os on it... How about that???
If Microsoft buys blackberry, bb10 would be dead as we know it. We would definitely see many bb10 components added into wp9 (yes wp9). We definitely won't see 2 different mobile os systems. If Intel can deliver an efficient x86 mobile CPU, look out.