Giving this thread a BUMP with some updates from the September Direct, updates are in the initial two posts of the thread but Nintendo's 2019 line-up is solidifying.
At the moment we don't have confirmed developers for these new games (other than Town), so I've listed them alongside the likely studio: Animal Crossing and NSMBU DX from EPD; Luigi's Mansion 3 from Next Level; Yoshi changed to Yoshi's Crafted World from Good-Feel; Kirby Epic Yarn port to 3DS from Good-Feel; Town from Game Freak; and belatedly added Marvellous' Daemon X Machina to the second post in the thread.
Right now Nintendo Switch 1st party titles confirmed for 2019 are:
January: New Super Mario Bros U DX
Spring: Yoshi's Crafted World
Fire Emblem: Three Houses
2019: Daemon X Machina
Town
Luigi's Mansion 3
Animal Crossing
Pokemon Generation 8
TBD: Metroid Prime 4
Bayonetta 3







