Next year is Gamecube 20th anniversary and Wii 15th anniversary, so I think that Nintendo will star selling more emulation ‘plus’ Gamecube and Wii games (same game with Full HD, 16:9 and buttons remaped for Switch, in Wii games case, motion controls re-design, like Sunshine or Galaxy) for a $20 price. Maybe they can also add online features to some Gamecube games (like Melee
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Nintendo has around 80-90 Gamecube/Wii published games.
Just think of portable versions of Luigis Mansion, Smash Melee/Brawl, Mario Sunshine/Galaxy/Galaxy 2, Donkey Kong Jungle Beat/Country Returns, Mario Power Tennis/Golf/Strikers (Charged), Metroid Prime 1/2/3, F-Zero GX, Eternal Darkness, Custom Robo, Baten Kaitos, Batallion Wars 1/2, Chibi Robo, Animal Crossing, Mario Kart Double Dash/Wii, Punch Out, New Super Mario Bros Wii, Pikmin 1/2, Rhythm Heaven Megamix, Wario Ware Smooth Moves, Kirby Air Ride/Epic Yarn/Return to Dream Land, Fire Emblem Path of Radiance/Radiant Dawn, Wii Sports/Resort/Play/Party...
It will be good fill up for some franchises before they release their next game on Switch next system.