I'm hoping that since they don't have to make one game for two different systems (like they did with NSMB, Smash, etc), it'll free up some of Nintendo's developers to maybe bring back some older franchises (Advance Wars, Punch Out, F-Zero, etc). Bringing all of Nintendo's titles under one roof should help a lot with droughts and shit. I also think that Japan is going to be all over this thing's dick. I still don't expect much from Western devs, however. Nintendo should try to get Dark Souls, Tales of, Kingdom Hearts, etc on the system.
As for being a console that can be made portable being a gimmick... I think it's a pretty fucking cool gimmick. But as a guy that likes playing portable games, I might be biased.
I also suspect that this is just one incarnation of the "Switch." I bet we'll eventually see a version without the screen for those who never play on the go (stationary version), and a smaller version with non-removable controller bits for those who want a more portable version. Iwata and other Nintendo devs did state that it was going to be a "family" of systems like I devices.