The Switch seems to have gotten a better reception than the WiiU, not only with the core gaming ausience, but with the casuals as well. All signs look like a comeback for Nintendo and the Switch being more successful than the WiiU.
However, 100m seems like a lot. Very few consoles reached that mark (GB, PS1, PS2, Wii, DS). For that number to happen, the market has to be just right. The GB was very cheap and had almost nothing to compete against (plus Pokemon and Tetris, two behemoths of their time), the PS1 was cheaper and took advantage of the problems of the N64 and the Saturn, the PS2 pushed itself not only as a console but as a DVD player while keeping the advantages of the PS1 above its competition, the Wii was a concept NOONE saw coming and was a hit due to les core audiences loving it and its competitors messing up in a variety of different ways, and the DS was the peak of the handheld market before mobile swalowed half of it.
The Switch will have to compete against two already established consoles and their derivates, a healthy PC market that keeps growing, and specially the monster of mobile gaming pushing handhelds out of their confort zone. Competition is a barrier for the Switch, and even if it's successful, it doesn't have the same potential growth as the Wii-DS, just because the market is so crowded.
With that said, I'm confident the Switch will put Nintendo back in shape. The format they chose has a lot of potential, not only as a good-looking product for both casuals and core gamers, but as the base of a hardware family that could appeal to a lot of people (a handheld-only unit for Japan, a home console only version as a bargain device, XL and mini models...). Even if it ends up selling only 60 million in 6 years, the Switch will allow Nintendo to put all their software effords on the same console, meaning more eficient profits.