The release of the Lite may change that though as now the plstform is more accessible to the portable side of the market with its pricing so users on that side of the fence who had yet to pick up a Switch will likely look at the usual flagship titles.

Bumping only 2.59mil more to go

let's see what this Mario anniversary will bring.. if extremely good (a Super Mario 3D all start is released), all attention will move, almost completely, away from Odyssey, if just a remaster of a single title it will make it.

Even with the remaster 20 mil still seems all but guaranteed.

It had a really good Q1 according to Nintendos report.

The game is still selling although at a slower rate than Super mario party and about the same as NSMBU deluxe although those games are a year or so newer. I expect it to fall behind Pokemon S&S, BOTW and maybe ACNH when the Q1 sales update is reported. Weird that it went straight to number 1 seller and could get overtaken by five games and drop to 6th very soon. Still i expect it to crawl to around 23-24m lifetime. So about 11 m more than the nearest 3d Mario, in any other era these would be standout sales but in this peak switch era somehow SMO is being over shadowed.

It just had a good quarter last time and with 2.5mil left and another 50-70mil NSW for the rest of its lifetime it’s all guaranteed now. Also a possibility of SMO and BotW becoming Nintendo classics budget sales later on

Also I think it's not unreasonable to say that throughout 4 decades of super mario the franchise has never been as big as it is now and i do wonder how many Mario games switch will sell. So far

MK8D 24.77m
SMO 17.41m
SMP 10.10m
NSMBUD 6.60m
SMM2 5.48m
MTA 2.75m
M&R KB 2.5m
M&S T2020 2M?
Total so far 71.5m

Most of these games are evergreens and this is just the halfway point of the switch's life with some of these games barely a year old and then add into the mix remakes, SM3Dworld deluxe, PM Origami King a winter olympics and another summer olympics game and maybe SMO2, SMP2, M&R KB2 then it could be possible that the umbrella of Mario franchises alone could shift close to 150m units and that is without including games led by characters within the Mario universe. This is just crazy and if by any chance MK9 is released then all bets are off.

It's a great game, I hope it gets there

This also doesn't even take into account for the fact that Mario is rapidly expanding into other forms of media (clothes, toys, theme parks, movies, etc.) In a way not seen since the early 90s. Yeah I'd agree that the brand is the strongest it has ever been and might even be Nintendo's strongest currently even over Pokemon.

SMO is definitely selling better than I thought it would.  In early 2018 I thought the cap was 16m.  

Looks like it's going to be close getting to 20m, and it may depend on what Nintendo does at this point.  Another 3D Mario game (or compilation) might cut it's legs even more.  On the other hand if it gets bundled again or put as a Nintendo selects, then it could go well past 20m.  It will be interesting to see how it turns out.