This was a surprising and disappointing outcome for sure, so I understand if some of us need some time to vent frustrations. It did seem like a done deal that there would be a trailer in this Direct and, uh, that didn't pan out.
Personally, I don't think this is something to be worried about yet. This was a smaller Direct and as was mentioned was aimed towards more immediate releases, with some far off 2022 biggies to get people excited, so AW was in an awkward middle ground. Plus, given the tons of marketing Nintendo gave to titles like FDC, WarioWare GIT and Dread, I think they might have learned their lesson regarding their nicher games and are just waiting for the right time for AW's marketing blitz.
Think about it. After Dread, what is Nintendo going to promote? They have Mario Party at the end of October, and then there's nothing until AW in December. And considering we already know most of what there is to know about Mario Party, I expect that most of their advertising efforts post-Dread will be focused on AW. Sure, they did miss a great venue with tons of eyes to advertise it which sucks and there's still no Japanese release date which also sucks, but I'm not seeing a lost cause yet.