you guys should also consider the play style of the switch and how it can be adapted to play vc games. the *ds family had the dual screens, and most game utilized both screens extensively, like for the main gameplay( zelda PH and zelda ST), or game manipulation( avalon code), or just basic stats(most of the rest). the wii games were primarily controlled by motion controls based of position detection, with a few game relying on gyro. wii u game had more classic controls with most games being playable without relying on the gamepad screen, but some games need the 2nd screen for stats and maps. taking the switch, it was shown that the 2 mode were mutually exclusive, both cant work together, either it is in portable mode or docked mode, not extended mode like the wiiu. *ds control emulation could be easy in portable mode, since it will be more like the smartfone ds emulation, but in docked mode, i personally would not find it good to map directional controls to the touch, as some games need accurate sketching( okamiden) or swiping. for wii , they would need some extra gimick for docked mode, though in portable mode, they could use the touchscreen. the patents show that there is an IR emitter on the device, but NIN has not confirmed it. Wiiu id just not feasible as there is no dual play on the switch, the device needs to be docked to play on the tv. of screen mode in some games may work, but game with no off-screen feature would have problems to deal with.
tl:dr; just read it.