From how it's stated and everything else pointing to it, it succeeds both the 3DS and Wii U. He wouldn't have mentioned the 3DS if the NX didn't involve a handheld in any way. I think a hybrid system is a bundle of both the handheld and console, but a single 'ecosystem' taking multiple shapes is what this sounds like. This might sound controversial, but if Nintendo is fully adapting Apple's model, they might actually make a single game library that both consoles (and possibly more) would be able to play. I know some people will say Nintendo is only referring to ports of the same game when they discuss easing software development, but I doubt that's the only thing they find difficult enough to warrant a new hardware approach.