Now it is late and Spak-Spang suckered me into making some more of my patented wall of text posts so I'm just going to throw out my idea of what I think would make a good NX launch.
Nintendo releases Breath of the Wild. Just like that, it's already a good launch. But to sweeten the deal, I expect Nintendo to release a new first party type of software like they've been doing with Nintendoland, Steel Diver, Wii Sports and Pikmin. The DS is the odd one out on that recent trend. It's the type of software meant to really showcase features of the new hardware (unless they feel Zelda does that well enough.) What that could be is hard to say but let's say the hybrid console theory is correct. The portable portion may be able to interact with other portables devices a la streetpass. Thus, it may be a game or minigames based on the concept of streetpassing but perhaps at a higher level of interaction or a next step that Nintendo has figured out to take with that concept. It could possibly even be packed in or preinstalled on the system depending on the size of the game.
Spak-Spang is right about a racing game usually being there close to launch though it isn't always Nintendo that's releasing a racing game. That said, I think if Nintendo was to have a racing game, I would turn to the F-Zero franchise and use that as a way of promoting the system and its online capabilities and infrastructure. Nintendo seems down on the sales expectations from a potential new F-Zero release so if they do want to give that series another kick at the can, making it available at launch and early in the system's life may be the way to give it the sales needed to make it a viable release option and get more customers than releasing it at other points in the console's life cycle. At least this way, Nintendo looks like it is giving the NX big support from the get-go with two franchise offerings at the beginning with Zelda and the lesser F-Zero which at least conveys more hardcore gamer appeal and support. F-Zero won't overshadow Zelda but it will still get solid hype just for being an F-Zero release after all this time. Much like Kid Icarus got a lot of press when the 3DS was promoted and launched even though it ended up coming out later than launch. You don't have to promote a racing game as much. Plus, if they do it right and have online racing, it could be a showcase for the NX's online capabilities as that would be a good title to use to highlight that Nintendo is serious about its online infrastructure being comparable to that of the PS Plus or XB Live and hopefully let 3rd parties see that they could bring those same experiences to the NX.
After that, its up to 3rd parties to make a splash like usual. Beyond Good and Evil 2 could help with that but the first game did not sell that well despite being a multiplatform release, IIRC. Thus, I'm not sure how much actual support a sequel would bring about in NX sales but it at least sends a message to consumers like the Bayonetta sequel that Nintendo does care about a core gamer experience. With Cloud appearing in Smash Wii U, perhaps an announcement of the FF7 remake coming to the NX can further seal the deal in winning over gamers that skipped the Wii U and giving the system a vibrant and strong launch.
After 2 months, release Fire Emblem Warriors, a sequel to Hyrule Warriors but with Fire Emblem characters designed to further help keep some of the kiddy image at bay during the launch period. That puts us in May. In another 2 months, if Pikmin 4 does exist and is not the 3DS game, then it might be time to release that. If not, then perhaps a new Mario Party would be an idea to give the system some multiplayer experiences or even better, a new Fortune Street further showing a stronger partnership of Square Enix and Nintendo. Or perhaps an RPG. Maybe Nintendo takes a chance with having Dragon Quest 11 released in North America a few months after its release in Japan.
In any case, the 4-5 month period after launch I would expect to be a bit quiet with titles that are interesting and have some appeal but may not be considered system sellers. They pad the line-up with different experiences at least. That puts to the end of August and start of September and that is when you start hammering the competition with some bigger titles like a Mario Platformer whether 2D or 3D. (3D would be preferable so the 2D would really have to hit it out of the park.) Mario Kart might be a possibility. Splatoon 2 seems reasonable to put out at this time with 2 years having gone by since the first one launched. Whatever Retro Studios has up their sleeve will most likely be a solid release. If the hybrid theory is correct and the 3DS is getting phased out, then perhaps there may even be a Pokémon game to have ready at this point. The cynical expectation might be a Diamond/Pearl remake but perhaps a new Pokémon Snap that one uses the portable portion of the console to take pictures of Pokémon in the real world a la Pokémon Go. With Animal Crossing: New Leaf now being about 4 - 5 years old, the public may be ready for a new AC experience. New Leaf brought the franchise to its best sales and Nintendo is clearly trying to cater and appeal to that market by focusing more on the AC franchise but nothing has worked as strongly as the main entries.
That's at least 5 titles which should all bring about big public interest in the NX and should lead to big sales all through the fall and winter season. Heck, maybe you even hold one or two back depending on what else may be available. Mario Kart I could see holding off until March or April a year after launch. In one year, you'll still have a system with Zelda, Mario, Animal Crossing, Pokémon, Splatoon, F-Zero and whatever Retro Studios is working on. Maybe Metroid maybe something else. That would be one of the most solid yearlong line-ups Nintendo has ever released on a console even if Mario Kart just misses the year mark. There's still a lot you can start prepping and have ready to release for the second year as well.
Finally, going back to the 4-5 month period after launch, even if Nintendo trickles out a couple titles, one thing that could be done to help keep up gamer interest and release more titles for the NX system could be the Virtual Console. But I'm not talking about VC games already released on the Wii U. I agree with Spak-Spang. Have the current VC ready at Day 1. That said, now might be the time to start releasing games for the GameCube and Dreamcast Virtual Console if Nintendo can work out a deal with Sega. With the titles for those 2 libraries, you could slowly trickle out games for them during this period as that would probably get a lot more interest than another re-release of NES or SNES games. Plus, there would still be indie games coming along at this time that may be of interest too.
Well, hope you enjoyed the Khushrenada NX Launch Fantasy. If you want year 2 of my NX fan-fiction. Just ask. Good night, all!