-- While there has been much speculation about a women's Royal Rumble, nothing has been "green-lit" yet but the belief is that if it happens, it will likely be a 20-woman Rumble. The other question is if having a women's Rumble immediately before a men's one would be overkill as the match would need to be at least 30 minutes in length.
-- Even though all the recent women call ups naturally points to a Royal Rumble, the real reason they were brought up is because WWE officials felt that with the same seven or eight women being recycled through matches, there was a certain "sameness" to the divisions and the call-ups will shake things up.
Source: Wrestling Observer Newsletter. Subscription information & prices available at f4wonline.com