The cart before the horse ethos that Hollywood has adhered to so strongly has hit its zenith of late. You don’t need a script, or a treatment, or even an idea, just a release date to plant a flag in and you secure a space for “Untitled TBD tentpole” or "Event Movie." Marvel’s certainly gone this route, Warner Bros. has followed suit with their D.C. Comics universe, so has Pixar, and to a lesser extent 20th Century Fox. You’ll only see this trend continue.
After Warner Bros. announced their TBD/DC Comics release schedule—one of which is the “Harry Potter” spinoff "Fantastic Beasts And Where To Find Them" and the anticipated additional spinoffs to come — the company announced dates for two more untitled animated movies.
Considering the success of “The LEGO Movie” (the second highest grossing film of the year domestically, number eight worldwide), pundits almost instantly started speculating the two dates could be 'LEGO' sequels, which THR quickly confirmed. Both films have already been slotted in for the coveted Memorial Day weekends of their respective years—May 25, 2018, and May 24, 2019—which is a big show of confidence as the original ‘LEGO’ movie arrived in February (and clearly was a much bigger success than they anticipated).
“LEGO 2" has already been slated for May 26, 2017 and “Ninjago” is set for Sept. 23, 2016, so these new films easily could be be sequels, team up movies, or spinoffs — the possibilities for this series and cast of characters is pretty endless.
Will there be other animated movies in store for WB besides 'LEGO'? Not for right now, as the company really scored with this franchise and plans to put all their might into the series for the foreseeable future. Of course, new projects will always go into development, but right now 'LEGO' is WB’s cash-cow in the animation wing of their house.