Donkey Kong is lower than expected, sure, but it still managed to give an increase of 1600 units to WiiU (by Media Create numbers), at a time when it would've probably been down without it. This, combined with the fact that Super Mario 3D World got a boost and is now again at the top 20 (number 12) are promising signs, in my opinion. The game will also have legs, of course, so let's see where it ends up.
As TheLastStarFighter mentioned, the game is probably not the kind of game that can make people buy hardware for it at once, but more of a game to get eventually, similar to the New Super Mario Bros games. These games still help sustain the platform in the long run in a less visible way, as evidenced by their legs. It's a cumulative effect, so I think you need to put the players in place (DK, MK, Smash, etc) and then judge the results in a time frame longer than a mere week...
But of course, I can be completely wrong and WiiU is just "doomed" or "dead", whatever that means in practical terms...
