With regards to third parties as well, rather than trying to negotiate a bunch of contracts with like 100 different publishers/companies, I'd say go for the head of the snake rather than trying to catch the whole damn snake.
I'd sign a deal with Square-Enix and EA primarily. Final Fantasy, Kingdom Hearts, Dragon Quest gaurunteed multiplats. Madden, FIFA, Star Wars Battlefront, too.
Agree to pay for half the cost of ports if need be for the first two years.
Allow Square-Enix to make Amiibo characters and put them in the next Smash Bros. Let them do a collaborative game with Nintendo characters so they can get a taste some extra money. Allow them to make a Mario RPG series and/or a Pokemon spin-off. EA gets to make Mario Sports titles.
Once you have strong commitments from these two, I think other third parties will hop on board, but even if they don't, honestly you could build a pretty strong library with nothing but these two companies, plus Monster Hunter, plus all Nintendo IP being on one unified platform.
Grovelling for every company and getting into pissing matches for exclusive DLC and all that nonsense is just something Nintendo doesn't need to be involved with. Get Square-Enix and EA (with a real contractual commitment).
