The Wii U would have been fine if it had launched with a Zelda title as well.
I don't believe that you can compare the two systems in the same way. If you want to simply go by financial success, then yes the Switch is a clear winner and will probably continue to do well. However the Switch still is suffering from the same thing that the Wii U suffered from, and that is simply a lack of good 3rd party games.
Sure the Switch certainly has more 3rd party support as of now from 3rd party developers, we have yet to see a good killer 3rd party app on the system.
But what about Skyrim and L.A. Noire? You will ask.
Well those games are in fact good. But they are six fucking years old. That isn't gonna cut it. The Switch NEEDS a solid non-Nintendo related game from a non-Nintendo company of AAA quality.
Give them props for including Indie support and a fairly great launch year of 1st party titles. But remember this, the Wii U was a great system. Games like Mario Bros. Donkey Kong Tropical Freeze, Yoshi's Wooly world, Mario Maker, Monster Hunter (1 of the 4 MH releases that occured in the system's lifecycle), and Bayonetta. There was some really great games on that system, but it failed for two reasons. One was poor marketing, and the other was the 3rd party support.
Right now, I contribute the Switch's status to both a better marketing scheme and a solid Zelda launch title.
What happens this year? We will have to see.