Doubtful, I think aside from the DS, the last home console of Nintendo's that was ever pushed to its max potential MIGHT have been the N64.

Maybe the Wii, but I get the feeling that due to schedule and budget contrastiants even its best games (save possibly Skyward Sword but I feel they probably could have done more with that)  could have been MUCH better, so the system was never really pushed to the extreme like we've seen certain SNES, N64 and even DS games that arrived late in those system lives.

Unfortunately I see the Wii U on that same path, Nintendo will of course do a lot with the system but aside from the Zelda entry they won't come close to maxing it out with their own internal studios, and they don't have the third party support that a major publisher would gamble on getting a team to do so. I mean Intelligent Systems, a long time internal Nintendo development studio didn't even know the 3DS could process feet for character models on battle cinematics for Fire Emblem Awakening, until it was too late to add it in development.

This. On SNES, N64, and Gamecube, they had studios like Rare and Factor 5 who were willing to make the investment needed to push  the hardware to its limits. Nobody really did that on Wii, and I doubt anyone will on Wii U either.

But just because Wii U will probably never be maxed out, doesn't mean there's not room for it to grow still. I expect there are games still to come that will exceed anything released on it so far graphically.

They have Retro Studio and the team doing the Zelda games. Those always push things further and further. 

Zelda games have been pushing the hardware a lot since the original Ocarina of Time. And Retro Studios are always achieving unmatched results despite going for a 60fps framerate. Granted, their Donkey Kong games don't seem to push the hardware nearly as much as their Metroid Prime games, but I am sure their next project won't be a new DK, so there's still hope. 

Yeah I hope Retro do something more ambitious for their next title, something that pushes Wii U the way their Metroid Prime games pushed the Gamecube and Wii.

Zelda is also a possible contender, but it's so up in the air at the moment; I'm not even sure if it will look like what they've shown so far, since they seem to be reworking it...

The fact that it's not being shown at E3 after they said they wanted to "explore new ideas" just has me suspicious, that's all.

Twilight Princess and Skyward Sword were reworked during production, if I recall.

At any  rate, if it does end up looking like it did at las E3 and December, it will definitely be contender for best looking game on the system in my view, and a further progression from any of their Wii U games so far.

Wii U is more powerful overall, yes. PS3 has the stronger CPU, but Wii U has more than twice as much RAM and a better GPU.

The thing with games like God of War and Uncharted is that one of their primary focuses was pushing the best graphics possible, and they poured huge amounts of money, resources, and manpower into making that happen. On Wii U, there is no such drive to produce the system-pushing visuals; Nintendo has shown no interest in pushing tech, and third parties haven't made the necessary investment to do so.

That said, there have been Wii U games that are beyond PS3 capacity, like Trine 2 Director's Cut and Xenoblade Chronicles X. But in general, few devs have actually tried to push Wii U's chipset, while many poured immense resources into pushing the PS3.