Note:time travel but not exactly and Time Baby as Anti-Bill
Future badass Dipper and Wendy both cyberpunk clothes and one with blasters and the other with a proto-axe leading a rebellion against Time Baby,while the present gang get in the fight. After learning about the Loki show and reading CodyLabs's works I wonder...since Time Baby is technically an extra dimensional entity who bends reality to his will does that mean he is like anti-Bill?Bill's messing with reality caused a ZK class end of the world scenario,it is possible that the time anomalies the Time Police cleans are actually the cause of Time Baby messing with time?his race is long dead,he doesn't care for "mortals" as long as he gets to oppress them,use them as marginally sadistic entertainment(like Globnar) or if they threaten his rule and there wasn't anyone to raise him so who's to say he didn't abused his powers and messed with time to become an uncontested tyrant and simply pretended as a keeper of time?(like perhapes preventing humanity from stopping global warming thus he got free from the ice)
it would explain why Time Travel is even possible because firstly it shouldn't be and secondly even if so by Traveling in time you would make alternate timelines hence why multiverse even exist so there shouldn't be paradoxes or any threat to the timeline you came from and why Time Baby felt so threaten by Bill that he personally came to stop him because if future is set on stone then why the risk?