Didn't John fuck up so badly by causing jade to die and Dave had to time travel to stop John being an idiot and left rid to stop existing. Would rose still exist and be all alone or stop existing
Terezi convinced John to go see his denizen early on and he tried to fight him and died. He couldn’t bring Jade in to the Medium so she was killed by meteors. That Dave then time traveled back and stopped John from going to see Typheus. The doomed Rose ceased to exist but her dreamself merged with Rose prime’s dreamself.