I think the Switch will absolutely get better support than the Wii U if only because it will be their only system. There will be now home console and portable, where the portable has better sales and more support while the home system gets left behind because no one bought it. Yeah, they will still support the 3DS for a little while (they've already said 2 more years or something right?) ut I think when the handheld stuff starts popping up for the Switch, when we have a new Pokémon and Yokai Watch and Monster Hunter people will buy one for those handheld games and now suddenly you also have a big install base for the home console only devs/pubs.
Now, I don't know how well it'll do compared to the PS4 and Xbone or how exactly "portable experiences" will be handled (you know, battery life, if the screen is touch, connectivity between devices) but I can totally see this doing at least as well as 3DS and Wii U combined and even better if they handle the marketing right. Only issue is the portability. It looks fairly big and certainly not pocket sized which is something the DS/3DS was perfect for.