Hey, fantastic idea for a thread!! I love positivity and foresight!
One thing I got running on the gameshell was PokeMMO.
The problem is, the resolution of the screen just wasn’t good, without plugging it into a TV. And of course, having to carry a keyboard to chat kinda defeats the purpose of it being portable.
The devterm will solve ALL of these problems.
On the topic of pokemon, the thermal printer is pretty darn close to the old Gameboy printer. Just saying, this could be the next best thing!
Nintendo DS emulation in general could be interesting, with the screens side by side. The track ball/nipple would make a fine stylus substitute.
Gaming wise again, having it as a steam link device could be fancy. Or heck, just running steam on it, using official Linux ports of games. It should be plenty powerful.