Title says all.
Probably more Pikmin 4 and 1/2 Switch (ugh).
TOTK DLC (possibly)
No Pokemon (saved for Pokemon Presents)
No Metroid Prime 4.
Fire Emblem will get another (ugh) game, probably an Echoes game.
I honestly believe they'll have at least something about Super Mario there; could be a whole new main game or spinoff or just DLC for some already-made game. Another 2D Mario game? That's... also possible, if you think about it, but I won't get my hopes up.
Maybe a "GameCube games for Switch" announcement.
More ports (probably ports that I will be excited for, at the very least, as I don't mind them at all).
Xenoblade Chronicles X? Hopefully? I say it's 50/50 at this point. Who knows if they'll ever bring it back... (I hope so.)
More VNs (kinda goes back to what I said about ports but this especially will be there).
ActRaiser Renaissance 2? Well, that's more of a hope for mine.
A remake of an old NES/SNES game or series (in the same vein as ActRaiser)? Perhaps... Perhaps not...
Stray could make it to Switch for all we know.
No Switch 2. No sight of a Switch successor at all, in fact. Probaby not going to happen till 2024 at the earliest.
Tetris will be there in some capacity. Maybe a new Tetris game like the 99 one.
My guess is that this Direct will also be heavy on the ports and third-party games (but I could be wrong). Even if it is, there could be a lot of neat surprises, as has happened in the past.
No Super Smash Bros. It's not happening anymore. Probably not for another 5 years at the least and if we're lucky. And either way, I don't want another one for a long, long time. Super Smash Bros. Ultimate was the ultimate Smash game. No need to already go into yet another Super Smash Bros. game yet again.
"Unsafe" predictions:
The Legend of Zelda series will get another game, possibly made by Grezzo or another third-party or another team. Something like one of those remakes or 2D games or even OoT/MM-like games. I know it's "too early" but, honestly, I could see it happening as they always have a "second line" of Zelda games alongside their "main" Zelda games. In fact, they'll probably try to hype the Zelda series to get more people to get TOTK.
Another out-of-left-field remake or continuation of a long-dead series could also be a thing, like bringing back Baiten Kaitos, for example (same thing happened with ActRaiser, as I said earlier).
Star Fox might be there, though I wish it would stay dead at this point or they sit on it before doing anything.
I could also see another new IP being there by Nintendo; I think it's even a good bet.
But those are the only surprises I see happening; like I said, there will be surprises... but it will be heavy on the ports, third-party games, and, I guess, remakes.
Keep in mind that this is kinda their answer to "E3" month so that's something to consider.
And they always have a "But wait, there's more!" surprise at the end of their Direct (so it could possibly be a bit more than 40 minutes long).
Tl;dr for my predictions: heavy on the third-party/port/remakes (which I don't mind) but still some surprises (as usual) and that's about it; I'm not expecting much from this Direct despite its length.
One thing I hope they don't do is show another Splatoon game or Splatoon DLC or Splatoon, well, anything.
I don't believe you.