As a "home console", it's going to be popular with existing Nintendo fans and probably not much more. That is, unless they've managed to make it nearly as strong as the competition and still relatively cheap. There are plenty of people in the west, especially North America, who really don't care about handheld gaming. That's not a group that this will likely win over.
The success of the Switch hinges on the people who still want a handheld device--and don't mind that this is nothing like the 3DS physically.
Beyond that, the real saving grace for the Switch is that it will (we assume) have Nintendo handheld and home console franchises, which together will cover any drought. 3DS and Wii U owners will probably buy it for that alone, as will some who would be on the fence buying a Nintendo product for either catalog individually.
The question is, will it create a meaningful amount of new customers for Nintendo who either come from another ecosystem or are new to gaming? I'm not convinced yet. A lot is riding on their first year release schedule of games.
