To be honest I don't think marketing is really all that important.
The SNES, GameCube, N64, Game Boy Advance, Wii U, 3DS, and even DS had average to mediocre marketing.
Nintendo is not very good at marketing hasn't been for a long time. Even Sega in the 90s took them to school on marketing.
What they need ideally are
1.) Bigger Nintendo IP earlier in the life cycle. Zelda at launch gifts you a free good launch period, but they need to have other big Nintendo IP ready to go in the first six months in addition to that. Wii U got Mario Kart, Splatoon, Smash Brothers, too late, one of these three needed to show up in the first six months.
2.) A design that doesn't alienate adults, Nintendo can get carried away sometimes in making things look too "kiddy", problem then becomes kids don't even want it (see also: GameCube). The Wii U tablet was ... ugly.
3.) The most important thing is they need a new break out franchise, or they need Splatoon to break out and become like a huge, huge IP to drive software adoption.
4.) Hardware that hopefully isn't so gimped that it prevents broader developer support. Less than the XBox One is dissapointing but understandable given the portable nature, it's just a question of how poor the performance is going to be, hopefully Nintendo doesn't gimp the chip too much.
