This is what I'm thinking:
1. They need to create a platform that allows the best looking and playing version of all major multiplatform games. Madden, FIFA, COD, GTA, Battlefield, Destiny, Ass Creed... all of these games need to be on NX, and realistically, should look and play better than the PS4 version of each game. Obviously some of those games get exclusive content on PS4, and I don't think there's much Nintendo can do about that until they decide it's worth it to money hat Activision for exclusive Nintendo-themed Destiny dance DLC...
... but until that day comes, the thing needs to be built from the ground up to be powerful and third party friendly. Creating a box that launches in holiday 2016 that is slightly more powerful than PS4 for $299 or less really shouldn't be that difficult.
2. They need to continue to create great first party software. This will be the primary way they differentiate from themselves and the competition.
Weird controller gimmicks are not necessary to differentiate. Great, exclusive games are.
3. New, first party IP is essential. Splatoon was a surprise hit, so here's hoping they have more confidence in releasing new IP going into the future. Look at some of the most popular genres out there, and create an exclusive game for NX with the patented Nintendo polish. That doesn't necessarily mean an "E for everyone" first person shooter featuring a colorful cast of cartoony characters. They shouldn't be scared of making some M rated games... hopefully they are aware that M rated shooters are the best selling games year in and year out. If you want to attract that audience to your console (and that audience is MASSIVE), you'll need to produce some exclusive, M-rated shooters on your platform. Good ones, too!
Bring back some old IP, while you're at it. Shocking news: SPORTS GAMES ARE FUCKING POPULAR. Bring back 1080 and Wave Race. Where are the exclusive NBA and MLB Nintendo titles? Also popular? SHOOTERS. Why not look into working with the Bond license for some Nintendo exclusive shooters? Again, one of the main goals with this gen should be to capture the MASSIVE audience out there that is playing shooters and sports titles on other consoles. Find a way to get them onto your console: one way is to create great games! Eventually, people will take notice and the status quo will change. At the very least, you'll grow the audience on your platforms for these genres of games and get the already established shooters (COD, Battlefield) and sports games (EA, 2K) on your console.
4. Moneyhat exclusives from third parties. Nintendo did it with Platinum this gen. Sony did it with Capcom (Street Fighter V). Microsoft kinda did it with Tomb Raider. What's stopping Nintendo from funding an NX exclusive Souls title?