I don't think these games lessen the diffence between PS4 and Wii U in any way. The difference is what it is, and it's fairly significant. I think they do show that beautiful games can be done on Wii U, and that the actual visual result as seen by the eye between systems is not overly significant. It's just the way it is, PS360 was already able to make beautiful visuals. 4One will make things even more beautiful if programmers put more and more effort in, but it will be in the little details, not the big ones.
As far as X specifically, the demo from the NDC was just to show the nature of the combat. It's similar in nature to Xenoblade, but with a mix of ranged and melee weapons, and a mix of on foot and vehicle combat which can change dynamically. It also involves a 4-player squad which is a nice step up from 3-player, and may or may not involve other human players. It was kind of a boring scene, but it did show that everything will happen in real time, in a vast, expansive, beautiful world. It looks exceptional, and more impressive than anything we've seen on last gen - though GTA5 would give it a run. It looks like a step down from a few titles shown for 4One, such as The Division and Witcher, however we've mostly seen only gamour reels from those games and nothing to be confirmed to be playing on a console. And basing on the Xenoblade experience, X most likely has massive zones all rendered at once, which is extremely impressive and creates an awe-inspiring experience when playing. Climbing up a mountain and looking down on the valley and village you just walked through is very cool and very immersive. This will probably be one of the best games of the generation.
And it was listed as a 2014 release in the Nintendo Financial report. I don't know why people keep saying it's for 2015 or later.