$299 USD is simply outside the price range of the family audience they're mostly targeting, hence why most buyers so far have been the hardcore Nintendo fans, and you can't float a successful console on hardcore fans alone.
What it needs is to be $199 USD, with Mario Kart and Smash Bros, (not necessarily bundled, but to fortify its library) to position it as a cheap and accessible family console to fill the Wii/360 niche once those systems bite the dust, which look like it won't be long looking at current sales. PS4/Xbone don't look like they'll be taking on that role any time soon, which leaves a vacant market for Wii U to exploit.
Now, I realize this cannot happen overnight, with the cost of the Gamepad still acting as a ball and chain. But manufacturing costs will reduce with time, as they do for all hardware. They could even do a lower cost redesign, a la the Vita slim.
They should at least cut it officially to $249 in time for the 2014 christmas season.