It's not clear what role he'll have with the company. It's believed that he's joining Nintendo of America (possibly Nintendo Software Technology).

Considering some people's reactions, there is one thing I would like to make clear, though. This has nothing to do whatsoever with Sega or the Sonic the Hedgehog franchise. He left Sega more than, if not a decade ago. The article even mentions that he had previously worked for Namco Bandai before he went to Nintendo. Personally, I don't know what will happen next, but for now, I'm going to assume that some good will come out of it.