Yea I guess you are right, just got a bit confused bc of japans sales

I'm going predict around 12 possibly.

BOTW*
SMO*
MK8*
Smash Ultimate
Splatoon 2
Pokemon LG
Animal Crossing
Pokemon Gen 8
Pokemon Secondary Title (either a remake or gen 9)**
Tomodachi**
NSMBU Deluxe
Luigi's Mansion

* = Already crossed 10m
**= Possible future games that are likely to be made.

Splatoon 2 will get there too. I also have a gut feeling that Luigi's Mansion 3 make it. It did ~5m on GC and 3DS, and I really see it growing on Switch (like pretty much every Nintendo IP is growing).

Luigi's Mansion did 3.33 million on Gamecube and 5.75 million on 3DS as of Dec 2017 (will likely finish around 6m).

It's a candidate for 10m but I'm going to go with 7-8 million.

Oh, I somehow thought it did 4.5m on GC. Thanks for the tip, Zorg!

And yeah, if LM2 is around 6m, I think 7m~8m is a safe number for LM3 on Switch.

Already:
Mario Kart 8 Deluxe
Super Smash Bros. Ultimate
The Legend of Zelda: Breath of the Wild
Super Mario Odyssey

Guaranteed:
Pokemon Let's Go Pikachu/Eevee
Pokemon Gen 8
Pokemon Gen 9
Pokemon Gen 4 remakes
Splatoon 2
Animal Crossing Switch

Possibilities:
Super Mario Party
New Super Mario Bros. U Deluxe

Puncher's Chance, but Unlikely:
Luigi's Mansion 3

That's all I've got at the moment and even then, Gen 9 and Gen 4 remakes are just hypothetical.

The one I'm most volatile on is NSMBUD, like I wouldn't be surprised to see 10 million plus, but I feel like it could also sell like 3-5 million. Yes we have MK8D as reference for how a Wii U port of a reliable 1st party title can perform, but MK8D didn't face the same competition from other 1st party titles like NSMBUD will. Now we have the big 4 plus Let's Go, Mario Party, and Smash. A new Switch owner has a great array of titles to choose from to purchase with their system. I guess time will tell, the only certain is of course the legs will be insane.

Oh, yeah, completly forgot about Super Mario Party. I'm thinking it will ship 5m this quarter, so it has a decent chance at reaching 10m eventually. Btw, I would say Luigi's Mansion falls in the same category as it (a possibility, not a wild card really).

I would add a new 3d mario game (Odyssey came early so I guess they will have the time to release a new one)!

Also what about mario maker 2? First one did great for wii U (around 4M) 

They both sold ~6 million on 3DS so I guess people think since many series are showing growth on Switch that these will as well.

I dont see 10 million happening but I could see moderate growth happening so 7-8 million.