I'd say Capcom, Namco, all of Square Enix (it doesn't make sense that just the "Enix" side has dev kits), SEGA (+ Atlus) and Tecmo Koei. All of them, more or less (between partnerships, collaborations and "mere" support) are key partners for Nintendo. I'd dare to say that there could be some Western devs who already got them. My mind goes to devs like Activision/Ubisoft/Warner Bros., Western developers who are still releasing games on Nintendo consoles, and some of them are quite important for the usual Nintendo environment (Activision: Skylanders; Ubisoft: Just Dance; Warner Bros.: Lego - games that sell well, if not the most, on Nintendo platforms in US at least).
...It's also true that this kind of collides with that rumour from the BitBoy developer, who seemingly got dev kits already, at the point he was implementing special features in his game compared to the Steam version. Quite specific new features, that could involve scrollable shoulders.
Maybe the process is a bit different for indie developers? Maybe other tools that don't necessairly require physical dev kits are enough for them?
My bets:
Sega:
- Sonic 25th Anniversary game (both the main console game, and possibly a second more handheld-oriented game by Dimps, the usual)
- Super Monkey Ball (crushingly absent on Wii U
)
Capcom
- Monster Hunter X Ultimate
- Monster Hunter Stories (more of a straight port, I don't see a G release)
Bandai Namco:
- Tekken 7
- Tales of Berseria (though Baba isn't exactly fond of non-Sony releases, who knows)
- Dragon Ball Xenoverse 2
- Ridge Racer 8 (VERY wishful thinking lol)
Tecmo Koei:
- Romance of the 3 Kingdoms 13 (Nintendo got 11 and 12)
- Whatever traditional Warriors game is out at the time (aside from Hyrule Warriors)
Level 5:
- Yokai Watch (3?)
- Ni No Kuni 2
- Layton?
Activision:
- Skylanders 6 (would love to see a Superchargers port with a higher-quality DK figure released...)
- Call of Duty (would be Current Infinity Ward's game, ugh)
- Maybe a Platinum-made licensed game?
WB:
- Lego
- Batman Arkham Knight?
EA (...)
- Madden
- FIFA
...
Ubisoft:
- Assassin's Creed
- The Division?
- Rabbids (hard to predict since it's very quiet lately)
- Rayman? (also hard to predict with no indication of any new game)
All for launch or near.