It will sell about 70-75 million IMO if they execute properly (50-55 million portable variants, 15 million-ish of the home TV version). Which will be more than the XBox One this generation but probably not as much as the PS4.
People are confusing "hybrid" with "fusion" they are not the same thing, what Iwata is talking about is multiple devices that play the same games, like iPad, iPhone, iPod Touch are all separate devices, but the apps and OS are the same across them.
Nintendo's problem is while the Fusion does address several key needs for them and allows them to leverage their overall hardware base better, it still doesn't address the issue of smart devices chipping away at their handheld totals, and that decline will likely continue to impact them in the coming years.
But still at this point I think it's their best play. 70 million is still a plenty large userbase to sell a lot of software on and big enough that probably a lot of third parties will support it too (even though Nintendo really won't need as much support with all their software backing on one platform in essence).
