I think most of what they announce will be what they will release during the NS's launch period before E3. In fact, I don't expect them to announce any real surprises since E3 will be just around the corner in 3 months or so. I don't even think they'll go into any real detail about the next 3D Mario or anything else they hinted at during the teaser reveal. Now, while I think the reveal event will be light on surprises, I believe that Nintendo's 2017 E3 will be one of the most jam-packed events they'll ever do.
As for what they'll reveal, I think BotW, a lesser IP like F-Zero and a proof-of-concept title like Wii Sports/Nintendoland along with some Wii U ports like Smash 4, MK8, Mario Maker and Splatoon will be what they give out from a 1st party perspective. A couple of significant 3rd party ports like Skyrim Remastered, Mass Effect, CoD, Overwatch and hopefully FFXV along with some yearly sports titles should be enough to give the NS a solid launch window lineup until E3. What I really hope happens is that Rockstar announces that RDR2 will come to the NS because that would do a lot to convince gamers that the NS will be getting legit 3rd party support.







