What’s not speculative is that adblockers have to be constantly maintained to remain effective. As websites find new circumventions, adblockers respond with fixes.
Manifest v3 freezes the capabilities of adblockers in time (it regresses them). Perhaps it’s sufficient for today’s ads but over time websites will take advantage and the effectiveness of adblockers will wither: websites have a financial incentive to circumvent all those chrome users.