It is dubious the Beforus trolls will even be in the show, at least without their roles severely diminished. They are one of the easiest things to cut if they need to streamline Homestuck to be adapted in a limited amount of seasons. Conversely, if the show is super successful and they are able to expand the animation projects, I would believe they would make a movie about the actual main Beforus trolls before their ancestors.

The Beforus ancestors weren't even in the main comic, the chance they would headline an animation project seems very unlikely. At best we get an official spin-off comic or something, but honestly I don't expect to hear from them in an official capacity ever again.