The Wii U also is supposed to have a disk that has half the capacity of the PS4's. I wonder how much of an impact that is.

I see three different possibilities:

1. They can't.
2. Games will use 7gb and will have to be HEAVILY downgraded to work on the Wii U.
3. Games will use only around 3gb and will be moderately downgraded to work on the Wii U.

Very little.

Not likely with similar performance unless the PS4 game in question is a small scope title.   It's also going to vary depending on the game and game engine (how each utilizes the consoles).

However, I won't go into any details at this time, I can say that any title that is expressesly developed with the PS4 in mind first ported to the Wii U would require reduction to the displayed graphics and possibly other facets via means similar to how PC games are toned down to run accordingly on lower spec PC's.   It's still very much the same game just with reduced resolution, frame rate, on screen enemies, physics, shader operations, etc...

syntax error... wii u wont get 3rd party games :P

games have high scalability so i dont think it is much of a problem.

It can't lol. Hell it can barely run current gen games, hence MGS5, GTA5 etc not coming out for the Wii-U. Forget scaling down... next gen 80% of the big profile games will run on the Unreal 4 engine, which Epic already said, wont even work on the Wii-u...

The Wii U will continue to get multiplat support as long as the last gen consoles do. Once thats over the umbilical willeth be snippeth! Big boy games will be developed when the the PS4 and 720 build up their marketshare.

Sorry, devs, and no Wii U is easier to develop for. To make a game which pushes the PS4 simply taes more time, it's a more powerful system. To make a Wii U game, all they have to do is use the engines they already made to make PS3/360 JRPG's.

We're already seeing Wii U lead the Japanese Market, no major Japanese developed game has been announced, or even hinted for on the PS4/NextBox, but Wii U already has several Japanese games. X, SMT x Fire Emblem, Bayonetta 2, The Wonderful 101, Dragon Quest X, Monster Hunter 3 Ultimate, etc.

Last gen, the PS3 sold less then half of what either the PS1 or PS2 sold in Japan, where the Wii sold 2-3x greater then the GCN/N64. Heck it sold about 75% as well as the SNES and 66% as well as the NES. Nintendo regained its hold on the home consoles in Japan, and I think it's because Japanese devs are smaller, and just don't have the resourses to make a high graphic exclusive.

Then why didn't Japanese 3rd parties not use existing engines of PS2 and make their games for the Wii? Most of the support was for the harder to develop for PS3. Even if the Wii sold more, was easier to develop for, PS3 still had the better support. The situation won't change next gen, in fact PS4 will see more support due to the dev friendly architecture.

WiiU Japanese support has been pretty weak. DQX and MH3U are both ports. When its E3 and TGC you'll see how much support PS4 has.

Because back then, Nintendo's reputation as a console manufacterer, were destroyed. Even then, Wii still managed to aquire a reasonable list of JRPG exclusives (Tales of Graces, Arc Rise Fantasia, Tales of Symphinia 2, Monster Hunter 3, Dragon Quest X, Dragon Quest Swords, Rune Factory, Fragile Dreams, etc) even if some of the bigger ones were 1st party. Remember, a lot of Wii JRPG's never got localized. Next gen, Wii U will get more, and PS4 will get less, simple.

LOL, when it's E3/TGS, you'll realize that PS4 will be abandoned by the Japanese, much like the PSV was. Well realistically, not as extreme, but I wouldn't be surprised if FFXV turned out to be a Wii U exclusive.