I would love to see any type of networking brought to the 7800, whether it be a ComLynx module or built-in ComLynx port to the 7800 ROM boards. Then we could add
Slime World
BattleWheels
Super Skweek
Double Dragon (the 7800 can do better than what showed up on it, right?)
Robo-Squash
And then (non-comlynxable)
Kung Food
Pounce (haven't played it, but it looks like a decent platformer)
Any RPG that was supposed to be released for the Lynx, whether it be Eye of the Beholder, Dungeon Slayer, Distant Lands, they would be good to have.