I agree with the OP, NX does not need to be on par with PS4 in terms of power to be successful, it doesn't really need a huge level of third party support either, though some third party support will help for sure.
Wii U doesn't lack third party support because it isn't powerful enough, it lacks third party support because the install base is too small and because the third party titles it got sold terribly, and it has been that way for Nintendo since the N64 and especially the Gamecube days.
The original Xbox had a similar install base to the Gamecube and most of the multiplatform titles looked the same, yet the Xbox versions of FIFA and Madden outsold the Gamecube versions with something like 5 to 1 and for titles like Call of Duty and Medal of Honor it was 3 to 1.
With the 5-fold increase in install base with the Wii, these kind of games also sold roughly 5 times as much. But still FIFA 10 only sold about 1 million copies on the system. "Yes, but it was a much shittier version than the HD counterparts", true the PS3 and Xbox360 versions outsold the Wii version, do you know which other versions outsold the Wii version? The PS2 version and the PSP version. That's not on better hardware, but it's on a systems that are branded for that audience.
Nintendo's consoles will never be the prefered consoles for the GTA, FIFA, Call of Duty, Assassin's Creed, Battlefield or Madden crowds. They are not gonna buy a system from the "kid" brand Nintendo, for which hardware those titles have never had a strong history on. They know that Sony and Microsoft will satisfy their taste for those games, because they have always delivered the latest instalment in these titles for years.
What Nintendo really needs is to offer something different that could appeal to families, and they need to have a strong library of Nintendo games on their next system. Both things are something a hybrid console can do. On the software front they need to bring out all their major first party titles, Mario, Zelda, Metroid, Smash Bros, Mario Kart, Pokemon, Star Fox, Pikmin, Donkey Kong, Luigi's Mansion, Fire Emblem, Advance Wars, Animal Crossing, Xenoblade, Kirby, Splatoon, Paper Mario, Mario & Luigi, Yoshi (and Bayonetta, which isn't true first party) with strong entries in all of them, this way they'll be sure all of the existing Nintendo fans will buy the system. They need some third party titles, for instance: Monster Hunter, Dragon Quest, Yokai Watch, Bravely Default, Skylanders, Shin Megami Tensei, Persona, Rayman, Kingdom Hearts, Final Fantasy, Resident Evil, Sonic, Beyond Good and Evil.
With other words: Japanese games, kid friendly games, games with a strong history on Nintendo platforms and obscure games you can't find on competing consoles.
