Any slight chance of a colossal failure to meet 100 million after such a strong start I feel has pretty much been squelched with the virus outbreak. It's boosted the sales of Switch significantly as people are staying home. Given that this is a handheld, and one that will likely have additional new models (and more than one owner per household), not to mention a ridiculously vast library of software - there's almost NO chance of this. Not only will it easily cross 100 million, but I think it's quite likely to cross 150 million at this point.
Would love to see it pass 150 million, I'm a huge Nintendo fan (though, not a fanboy and very critical). However, honestly asking, do you see any realistic chance to meet that goal or is it just a dream? I thought about it and if there is a slight chance for that goal, everything would have to line up:
1. The Nintendo Switch needs a very long lifetime (more than 7 active years), in order to have that:
2. Nintendo have to push out great quality software even in its late years. One of it has to be a surprise hit like Wii Sports/Wii Fit/Brain Age/Nintendogs but of course, it has to be something completely new, Brain Age on Switch doesn't make numbers as we can see.
3. Indy support is guaranteed but the Switch also needs ongoing support from the big players, most of it will be old and late ports but at least some new (AA) games need to be there as well for the prestige to show that the Switch offers everything/can handle everything.
4. Keep on (aggressively) marketing and advertising the Switch and its software
5. Additional SKU's, they are always minor or bigger system-sellers. Cheap ones to have several consoles in one household and releasing a Pro together with a game that shows the advantage of it like Metroid Prime 4 and/or Breath of the Wild 2. With it, get in more core gamers and early adopters who are ready again to lay down money for a new quality product.
6. Related to 5.: Don't call the successor Nintendo Switch 2 and just count the sales of it to the sales of the Nintendo Switch family. They did the same trick with the Game Boy Color, although, it was actually a new system, a real successor. It had everything what qualifies as successor: Technically significantly advanced (hell, graphics in color vs. green-gray only is a huge difference) and its games can't be played on the predecessor. I think, this point will be the single most deciding factor in reaching the 150 million!
7. Price cuts and attractive bundles, with the former Nintendo will wait as long as possible but eventually we will get them.
8. Xbox Series X and Playstation 5 don't have a significant adverse effect on the Switch sales (a very likely scenario)
9. No strong direct competitor, i.e. no strong hybrid competitor (a very likely scenario)
10. The full potential in Europe and rest of the world has to be used. The sales in Europe are still not where they could be (some aggressive marketing is necessary there). With a long life cycle, hopefully in the rest of the world those additional 5 or so millions can be sold to help finishing the line.
11. No recession and no crisis (the current Covid:19 crisis actually helps the sales)