We might as well also look at the actual Gibbogame tweet (and note, this guy isn't exactly an expert translator so the original meaning is probably garbled too):
Iwata - we are preparing for next generation hardware as always doing, when release? Difficult to declare..
Iwata- not hopeless or at a loss in coming up with something new but unless existing users satisfied we cannot release next hardware
Nothing about SEGA or supporting the Wii U through 2016/17 was mentioned at all, so some people should settle down a bit. "Satisfying exiting users" could just as likely mean giving Nintendo fans that have a Wii U the standard fill of Nintendo IPs -- your Marios, Mario Karts, Smash Bros, DKCs, Zeldas, and probably a Metroid thrown in there at some point. In fact I think that's more likely what Iwata meant.