Released 2 months after the reveal? Not buying it (although I will definitely be buying the thing). I don't think Nintendo will launch with something as guaranteed as the next MK9 (or at least without something for the "hardcore gamer" market like they did so well using BotW for), but I'd be thrilled with it given 8 came out 10 years ago on Wii U.
The 3D Mario is also another "oh really" eyeroll. Christmas at the latest surely. MK was previewed as a launch window game for N64, GCN, Wii, Switch, so I'd definitely hope/expect to see a peak in the reveal video.
Surely they'll want a launch game to properly differentiate the new system, which was arguably an issue they never addressed with the Wii U until 2015 (the system's last gasp) and Switch was all about rectifying these missteps.
The only thing that lends itself to a close to reveal launch imo is the fact that images of the thing are possibly "leaking". Hope I'm wrong, but where is the time to ramp up a marketing campaign etc.
Either way, hurry up Nintendo.