I do think its a good idea, but the format has to be studied.
I think it must be a portable wich can connect to the TV and be a console aswell (the key feature beeing that it must look like a portable system, wich is a market Nintendo cant risk losing). But, this might be harder than it seems to pull off because first it must match next gen technology, it must be priced reasonably and must use a media storage that is capable.
This device having the full undivided atention of Nintendo development would no doubt become a more atractive proposition than the 3DS and the Wii U are separatly.







