Yes, I think it can outsell Wii if they make the right choices- they need to keep a great flow of 1st party software, and hopefully the third party pipeline will increase. I guess pricing could eventually kill the legs for Switch too, but that's not hard to change.
Wii, IMO, could have sold another 20 million but Nintendo's software strategy started going down the toilet in the last years with fewer and fewer games and a big focus on GameCube-like software. Wii is also a bit different because it had an amazing concept that was quickly encapsulated in Wii Sports.
I think Switch has an amazing concept too (2 player games anywhere, anytime), but maybe it's not as "obvious" as Wii. Then again - maybe it is, look at the sales!
I think a better comparison than Wii would be DS, which I think hit about 120? Switch, for all the talk, is actually a handheld console, and as such it can eventually sell like one. Switch is actually off to a better start than DS or 3DS from a software perspective (and I think from a sales perspective too - haven't seen a DS and Switch launch-aligned chart).
Many folks will declare that mobile kills the handheld sales potential for Switch. I disagree, for the simple fact that I can't play Zelda or Mario Kart or Skyrim on a smart phone or a tablet.