I wouldn't like it to be a hybrid. Except (as said in other posts), a handheld that can connect to a TV (and maybe accept controllers), that's ok as long as it can completely be used as a handheld.
The reasons for it is that if it's something in between, devs will start trying to please everyone (the ones playing on a big screen and the ones playing on the small screen for example) and get something as coherent as Windows 8 (which exactly tried to please two sides, computers and portable smartdevices).
Then, the only thing I'd like for it is... games. That doesn't seem hard to understand for a game console, but then, why does the Wii U have like 2 interesting games ?
Also, stop doing weird versioning, like "the New 3DS has pure style with colored buttons and faceplates, but the XL --the only ones that you can use with your long fingers-- only comes in ugly colors, has no faceplates and the limited versions are printed upside down" -.-