40 minutes
I'm looking forward to more Pokémon of course, but I don't want them to reveal too much more really. I want Sword/Shield to be massive and have the fun of exploring it and discovering new things without knowing about them in advance. I know they'll probably leak, but hopefully I can avoid most of it for a few days at least!
I expect Pokémon and Luigi's Mansion 3 to take up less than 15 minutes combined, maybe even closer to 10 minutes really. So, that leaves in excess of 25 minutes for other games. I'm sure a small amount of time will be used to plug the Switch Lite and Zelda, along with the Witcher 3, Overwatch, Daemon X Machina, Spyro, Ni No Kuni, Ori, Super Monkey Ball, the latest Layton port and maybe a few indie games.
There will be more though... I think there will be a previously unannounced game and another Wii U Port (hopefully they're not the same game). Most rumours are pointing toward Pikmin 3 being the port, with Pikmin 4 likely coming next year. It could be Xenoblade Chronicles X, Wonderful 101, or Mario 3D World as well though. Still also hoping for Metroid Prime Trilogy, but I think that might have been saved for 2020.
We probably won't see Bayonetta 3 yet either, as the tweet specifically says 2019 games... But, they might surprise us with one 2020 game to close out the show.
Oh, and this is probably where they add SNES games to the Online Service bundle and possibly charge more for it.