If Sony stopped manufacturing the PS4 in Q4 2016 the Wii U wouldn't be able to close the gap... So I say no.
The big problems here is that PS4 has a lot of 3rd party muscles. Even if Sony doesn't releases anything, there will be big budget marketing heavy mega hits. That's what sells it. It has a decent power/price ratio too, something that drags the Wii U down for next gen consoles. People want a console that gives a real jump over PS360 and that's on PS4 and X1 only. Or you have to give something more, like the motion controls on the Wii. But the Wii U gamepad simply isn't a innovative idea because it doesn't add any significant feature to gameplay, it's not a game changer like the Wii mote that created new genres and things like that.
Nintendo is trying to relly on having a massive new idea every gen, but things don't work like that. You innovate, but you have to create a solid plan if you innovation isn't the game changer. Think Project Morpheus. VR. What if it flops? Well, it will be a the new PS Move. So what? The console isn't built around it. If it was there day one (as the gamepad) and it flopped, PS4 would be dead or at least damaged (see X1 and Kinect). So yes, if Nintendo doesn't stop relying on crazy things as their only pillar, they will end up out of the home console market. Like Sony would end if the PS4 was made with the same thinking line that created the PS3. You can't do a mess every gen and still be on business. You are allowed to ruin one, but several in a row it's a death sentence.
Returning to the comeback, it isn't possible because in gaming history being overtaken only happens when the lead company does several mistakes in a row. Because after you are in 1st place, you can reduce your pace and even do one or two idiot things without losing your spot. The PS1 overtook Nintendo, the Wii overtook the PS3, the PS4 overtook the Wii U only because the previous leader screwed everything possible he could screw. N64, PS3 and Wii U, at launch time, simply did almost everything wrong and managed to burn a previous gen leadership to the ground in 1 or 2 years.