Aside from the rumors, we can map Nintendo's teams. Assuming structure remained roughly the same since EAD and SPD became Nintendo EPD, we can see:
Nintendo EAD 1 (Mario Kart): this one's halfway likely, since they're roughly a 2.5 year/3 year team, although my guess is they'll get their game out by Holiday 2017.
EAD 2 (Wii ____, Splatoon, Animal Crossing), their last games were both last year, but we could see smaller stuff for them at launch, the rumored Splatoon Remaster and maybe a downloadable tech demo.
EAD 3 (Zelda) basically the only sure thing out of this.
EAD 4 (2D Mario, Pikmin), we could see Pikmin 4 and the Mario Maker remaster from this team.
EAD 5 (Nintendo's share of Star Fox Zero, other oddities), maybe the proof-of-concept demo will come from them instead.
EAD Tokyo (Mario), perfectly timed for the next 3D Mario from 3D World in 2013.
SPD (Team Sakamoto), it depends on how much work they put into Rhythm Heaven in 2015, otherwise their last "big" year was 2013. Could we see a new Wario Ware? I'd say this is also our best hope for Metroid. Either way, i think it will be launch window and not launch.
With that in mind, logic side from Nintendo says:
Remasters of Smash, Mario Maker, and Splatoon
Zelda U
3D Mario
Pikmin 4
A Nintendoland-style tech demo.
Seems like a lot, but Nintendo also definitely wants to go big here and knock it out of the park. Three remasters feels like much even then, but one of those three is a lock and two will be there by the first holiday.
Third party is the question.