That's a meaty Direct. I still wouldn't expect to see anything of 2018's line-up, beyond perhaps a surprise announcement. This four month patch is Nintendo's busiest for several years across first and third party.
I expect they'll touch on the just-released Monster Hunter Stories, and on top of that, 3DS has Metroid: Samus Returns, the Virtual Console releases of Pokemon Gold and Silver, Fire Emblem Warriors, the multiplayer Kirby title, Layton's Mystery Journey, Apollo Ace Attorney, Mario & Luigi: Superstar Saga remake, and of course, Pokemon Ultra Sun and Ultra Moon coming this quarter - there might also be some news of eShop titles for 3DS.
Switch has ongoing DLC support for Arms and Splatoon 2, which might get touched on, as well as the story DLC for Zelda, which I think we should see a proper trailer for this time. On top of that, Nintendo will also be publishing Pokken Tournament DX, Fire Emblem: Warriors, Super Mario Odyssey, Xenoblade Chronicles 2 and Skyrim (Switch version is Nintendo-published) in the next four months. In terms of third party, there's Rayman Legends, L.A. Noire, NBA 2k18, Rocket League, Just Dance 2018, FIFA18, Worms WMD and Sonic Forces (at least). Add on undated indie releases like Stardew Valley, Rime, Yooka-Laylee and SteamWorld Dig 2 and Switch has a really good line-up for the next few months.
Between 3DS and Switch there's a lot Nintendo could cover, so 45 minutes makes sense even without much in the way of new announcements. Maybe we might get some info on something like Dragon Quest XI, but I also expect we'll be getting a couple more Directs before too long (November, January), and I expect Nintendo will save new announcements/details (subscription service?) and 2018 games for those Directs. In short it should be a full Direct without much in the way of megatons.