Oh, this should be interesting at the uttermost least. This is something I've been waiting for since I was equally hooked on Mario and Sonic as a child in the 90's.
I'll keep an open mind on this. I'm sure they'll find a way of making it seem more than just the ordinary party/mini-game. SEGA's Sonic games haven't been as universally acclaimed lately, but Shigeru Miyamoto will be supervising, so they'll be inspired to put in at least really good effort into this historic event.