Yeah it would probably require the touch screen etc. I can imagine playing games like Samus Returns, Luigi's Mansion 2, Fire Emblem Awakening, Monster Hunter 4, Animal Crossing New Leaf and Mario Kart 7 on the Switch's bigger screen. There are a lot of cool gems on the 3DS that I feel could go well with the Switch.
Lets face it, they would never do this tough. Why give people an option to play their DS/3DS games for free when they can charge 10-20 bucks for them on the Eshop?