Now that Disneyland Paris has officially announced a third gate, it seems logical that stateside Disneyland Resort would not be too far behind in announcing it's long rumored 3rd gate. The new paris part is estimated to open by the end of the decade. It is reasonable to expect DLR to not stand idle, and that an announcement of a new park may take place in a year or two,..around the same time as an official announcement of Phase II of the DCA makeover.
We should expect a waterpark, too. Granted the waterpark (designed in part by Disney Imagineers) would be part of a residential community connected with the DLP resort. Nevertheless, DLR's new competitive mindset wouldn't allow itself to not continue what would be a trend in Disney waterparks being a high profile part of the dynamic of resorts. Orange County weather will not cause DLR to perhaps end up the only resort without a waterpark....as I'm sure that other Disneyparks (overseas) without waterparks will soon have them. It also looks pretty bad for WDW to have two, and DLR none.
Source (of DLP 3rd gate annnouncement): Disney And More
Projection of DLR theme park three announcement: myself