Went into a UK GAME store today (to buy Wonderful 101) and Wii U has a tiny little bit of shelf space in the Used section, plonked next to used Wii and DS games (new Wii U games and systems though). For the rest of the store, one side is PS3, other side is 360 with heavy advertising for PS4 and X1. Bit of Vita, bit of 3DS, bit of PC and oddly, iPads.
This situation will not be improved by Mario, DK and Zelda. Come November/December, it will be all but gone. At this point, I don't think even dropping the price to £99 would help, nobody wants it.