Yeah, I can also easily see Switch hitting the 100 million mark at this point, it's just so versatile and the games library is possibly the best Nintendo have ever had. Great indy and 3rd party support too, just ticks all the boxes this time round!
Sure, I agree with you to a point. But that doesn't mean it should do double the numbers. Think about it, how many people owned a Wii AND a DS... like pretty much everyone, right? That's two sales right there, whereas Switch you only have ONE sale and it covers both handheld and console.
So covering two markets consolidates the sales figures, it doesn't actually double them. Having said that, I can certainly imagine multiple Switch households, what with kids having their own ones each, certainly the portable Switch lite model. So it may end up doing DS numbers rather than Wii numbers, but I doubt it will do DS + Wii numbers unless shit goes absolutely bananas!