This is taken from Smashboards.com so I won't claim credit for it, but has anyone noticed this?
Enter this address into your browser:
http://www.smashbros.com/en_us/images/icon/world_b_01.gif It's the SSB icon.
Now change the number "01.gif" to 02, 03, etc.
These are the icons of the SSB franchises which are being represented with at least a level. You'll cycle through all of the existing franchises from 1 through 12, but 13 and 14 have no icon (yet), but 15 is the Animal Crossing icon, 17 is also missing, but 18 is the Kid Icarus icon.
Since there's no rhyme or reason to have missing numbers on the list from 1-18, we can safely assume that 13, 14 and 17 all represent franchises which have yet to be revealed but will be at some point in the future, a fact which is corroborated by the Franklin Badge update which placed the Earthbound logo at 07 where there was previously nothing to load.
We don't know if it goes any higher than 18, but we know that these three empty spaces will be filled with something. If two of these will be Ice Climbers and G&W (Dr. Mario was represented by a mushroom logo), then that leaves MGS, but if either ICs or G&W don't return, there will be at least one more franchise on the roster which has yet to be revealed.
I'm personally hoping the numbers will hit at least 25.