I can't provide a direct source that says EXACTLY what RWA stated...I'm under the same impression as RWA though and it must have been in one of the newsletters...or it could have even been a conversation here or on another message board.
Dave said in a newsletter (and a follow-up forum post) that the programmers had optimized the code (even for Uprising) for the CaW formula to the point where each saved wrestler (as in, the save file that contains the point-to information and size-scale changes) takes up less than 512 KB or so, minus the amount of space that the 3d models, textures, and music resources take up prior to picking your pieces in the CaW maker mode.
Okay Dave said before their are NO Limits to the amount of caws you can make. The only limit will be the size of your storage device (hard drive, zip drive, cd-r disc etc...).
Right. Minus resources (which'll probably add up to only a few hundred MB from the disc and a few hundred more from downloadable content over the first 2 years of release), then divided by 512 (Kb) to equal the amount of wrestlers you can put. MATH! WHOO-BOY.