It won't outsell it during the holiday period.
Vita is cheaper and it includes PS TV sales (which isn't even a handheld and is even cheaper than the Vita).
In the end, the Wii U will be remembered for its great first party line-up while no one will remember the Vita all that fondly. Most of its games are available on other platforms, the rest is too niche.
As for which console is the biggest commercial failure? Again, the Vita, just look at its list of million sellers lol. I don't think anyone expects the Vita to get a succesor, the Wii U will get one.
The Vita's legacy will be that of the Gamegear.
And the Wii U gets marketing? That's news to me. I've never seen a Wii U ad.