Improved OS is my #1 request. Particularly the eShop, which is a joke, currently. I'd also like for them to put two joysticks, but that's pretty much a given at this point.
I don't really expect or want it to be more powerful than todays mobiles. They could use the same hardware seen in this years top-end phones, but instead of going for a bleeding edge 1440p, stick to 540p. With a 3.5" - 4.7" screen, you're hardly gonna care. That should leave plenty of resources available for some nice looking games.
Oh, and the cheapest model shouldn't launch for more than $199. $179 would actually be preferable.
EDIT: I wouldn't mind them sticking with the clamshell design, either. Though dual screens aren't a must for me, it does help keep the display in better shape.
