It's not the cost of the disk that matters. It's a pain in the ass to split the game up and/or find new ways to compress or cut down on assets to make it fit. However that's not going to stop a developer from releasing games on the 360. You simply still won't see the extra space being used on the other consoles.
Japanese games might not bother with the 360 anymore and go for ps3/wiiU, but western developers will keep making their games for 360 first and porting to ps3 and maybe wiiU.
They both can't afford to wait too long. If the WiiU becomes too popular it might become the lead platform and then the ps4 and Xbox3 will be stuck with the ports. Sure the games will probably run smoother on those systems but if the wiiU can keep up we'll get the same situation as with ps2 and xbox, and only exclusives will use all the power of the new systems.







