If someone asked me "would you like to have one Nintendo device that has the output from all Nintendo developers?" my answer would be yes.
I'm not against a hybrid, not at all. My problem is that if they want to put 'current gen' games on a handheld, it will need space, a lot of it. Sure that's not a problem for those that buy physical, but I don't because Nintendo is not even in my country anymore so the prices are usually 2x the price of a regular PS4/Xbox One game.
As far as I've read about it, SD/MicroSD cards are hovering at 128-256 GB, with some more expensive ones going over that. I've also read about new technologies that are coming, but are not ready yet (Samsung has one, IIRC). Portable games are usually small, so 32GB internal memory would be fine (I have a 32GB Vita memory card myself, plus a 128GB card for my N3DS), but apparently the NX also needs to be a home console, and IIRC they already said / it leaked that the cartridges would be up to 32GB. That means games would get bigger, likely similar to the Wii U in size. If that happens, 32GB suddenly isn't enough anymore, and even the bigger SD cards would get filled very fast, compared to a 2TB hard drive.