Looking at it logically, how can it? Are all the 3DS players going to pony up hundreds of dollars to play better graphic games? Is the USP going to appeal to the masses in a way neither a handheld nor Wii U could? In a quick update of the situation and having watched the sizzle reel, I'm seeing nothing that'll sell these things en masse. If you want console games you'll get a PS4. If you want handheld games, it's a far from ideal solution and you may just stick with mobile or 3DS. I certainly can't see 5 million people rushing out to spend $400 on a Switch and a couple of a games.
The features are features without support so they'll die horribly. Motion controls in the JoyCons? Great. Nice little expense on MEMS but who's going to write games to use them? How many motion games were in the sizzle reel? They learnt nothing from Sixaxis... Same with HD rumble icecubes. Great little tech feature, but utterly useless and valueless in real terms. Doubt 1-2-Switch is going to sell 100 million consoles.
Even their online service is laughable. Every month you get a NES or SNES game for free! In the face of Games with Gold and PS+ Games, that's exceedingly cheap. Nintendo drag out their history generation after generation to the point its now an embaressment. Also from what I read, it doesn't include voice chat and there'll be a companion app on smart phone for that? PSN can be pretty crappy at times; I dread to think how miserable and buggy Nintendo online is going to be.
My personally only positive is that the engineering and implementation is pretty cool. The controls and way things piece together and the versatility and potential, it's a nice idea. But it sounds like something on Kickstarter/IndieGogo that gets 10,000 people to fund it at a wonderful sounding 5x goal, and then dies in the real world. Without a killer app to sell this console to 10 million in the first year and a raft of unique, Switch specific games to make it worth having, my forecast is that in 4-5 years we'll have articles talking about how awesome Switch was and how loved it is by it's few owners and wasn't it a shame it never got anywhere when it had such quirky games as Mario Horserider and Pokemon Salt and Pepper.