Before the Wii U I would've said a new Zelda or a home console Pokemon game but now... eh... probably nothing. I've been more critical of Nintendo since the Wii U, with its droughts and constant delays. It's a good game system, not my favorite Nintendo console but it's good, but it's just taken so long to start getting the games I really want (Super Mario Maker, XCX, SMTxFE, Zelda U, proper 3D Mario, etc.) that my patience with the system is a bit tired. I'm burned out on the system and will probably wait on the next Nintendo home console for a few years before buying it so it can build up a decent library.

It's possible for a Nintendo platform to have a launch line-up I can't ignore, but considering the current development schedules of their studios I deem this to be so unlikely for the NX that I might as well say Half-Life 3.

For instance, I imagine I would be tempted to buy a system at launch for a new Zelda game, or a new Xenoblade. Since Xeno X just came out this year, I doubt Monolith Soft will have a new one ready for the NX launch; likewise, with Zelda releasing next year for Wii U, it's improbable EAD 3 will be able to churn out another one so quickly. And no, Zelda Wii U "NX Edition" does not count as a "new" Zelda game. It's not a system seller for me if I already own a Wii U with which to play the game.

Nothing, I don't buy consoles at launch

hype sells consoles not games.

throw out lots of trailers of 3rd party games in turn tricking people into buying your console then let them wait for said games for who knows how long.

Uncharted 5

Pokemon XD sequel tbh

I'm probably not even going to buy the NX at all much less on day 1.

The closet I'll get to a day one buy is a new Kid Icarus Uprising-esque game, but I still wouldn't get it day one.
But I never buy a system day one never will. I also never pre-orderd, with the exception of Kid Icarus Uprising. Worth it but that will be the only game I'll ever pre-order

I don't do launch buys when it comes to consoles.
I'll buy it eventually once it's gathered that strong Nintendo 1st party library I'm looking for. UNLESS, it actually turns out to be all digital.
I absolutely do not care if the system comes with:
Galaxy 3/ Sunshine 2/ 64 2
Star Fox
F-Zero
Pokemon Gen 7 (or Gen 8 if the 3DS still has life in it at that time)
$150-$250 price tag
Metroid Prime 4
Or if Zelda NX is a direct sequel to my favorite game of all-time (Skyward Sword).
All Digital NX = No Purchase from me