Sure, sales potential the Nintendo 1st party titles are way ahead of those titles indeed. But there are similarities between the Vita and WiiU situation eventhough that the numbers wont be 1:1 to eachother.
Yeah, there are differences as well, but there are several of similarities too.
The similarities have been pointed out many times in this thread but the differences are more relevant in my opinion. While I agree that WiiU will have a rather weak 1st half year, it´s important to point out that WiiU already sold 2/3 of PSV lifetime sales.
-two WiiU games already outsold any PSV game, both games likely becoming millionsellers
-there is no known PSV game that has the potential to reach a million, even 500k is a stretch
-with MHTriHD three launch games soon will have outsold any released PSV game
further more promising things
-Pikmin 3 and WiiFitU are two further games that will outsell every released PSV game, even Wario Ware and W101 have a shot at outselling any PSV title
the most important differences are
-PSV launched after 3DS, while WiiU has a headstart against PS4
-Nintendo 1st party games of established franchises like Mario Kart, Smash Bros. etc.