I'm pretty certain it won't. The reason the last few have been backwards compatible is because they've been based off the same setup since the GC only modified. I don't think that will cut it anymore though and Nintendo will have to start from scratch. Probably something similar to PC in order to get third party support. However, this is Nintendo, so...
@Phantasos
Sadly I've found most of it rubbish. Played DK:Tropical Freeze but found it frustrating, SLW was quite forgettable, Splatoon had a good idea, but lacked in single player and general content, Starfox (sigh) loaded with pointless gimmicky vehicles that bog down the game, Mario to be pretty weak overall, MK8 inferior to the lush environments and modes found in SEGA AllStar Racing Transformed, Zombie u unplayable due to its design around the pad, never cared for Smash beyond the odd game and W101 poor. Bayonetta 2 was pretty fun, but it's been a really struggle for me to enjoy this console at all.