Depends on how the PS4/XBone do. They both seem to be on track to do amazing at both launch, and in the long run. If they do substantially better than the Wii-U, then yes, it is safe to call the Wii-U a failure at this point.
People keep calling the Vita a failure, yet even it is doing better than Wii-U. With PS4, chances are that it's only going to do better. But we'll see.