There’s nothing to be done that can change Harry ending up with the Dursleys. Honestly, given he’d been put with them days before Sirius was caught hunting Pettigrew and chucked into Azkaban without trial (while Dumbledore was conveniently head of the Wizengamot), there might well have been nothing that could have stopped Dumbledore’s decision. If Sirius hadn’t helpfully removed himself he might have been removed more permanently.