Maybe this will lead to more people using Firefox and other browsers
I would also expect this to cause a modest-to-significant backlash against Google as a whole. This is a change that will be widely noticed among regular internet users, and rolled out at a time when Google's bread and butter (search) is at its weakest point in decades.
Moving into purely speculative territory here, but I also wonder what impact this might have on their business moving forward. Without having hard numbers to back this up, my anecdotally-backed hunch is that ad blocking is disproportionately popular among younger users. That's a risky demographic for any tech company to alienate in part or in whole.
Once users are forced to both potentially replace their adblocker entirely and begin mucking around with config settings and filter lists it seems inevitable that many simply jump ship. Doubly so if the advice gets amplified across social media / streaming platforms et al.
The crowd you’re referring to - i.e who follow tech news and the manifest rollout - are a tiny minority many of whom probably never used Chrome to begin with. That’s not who I have in mind here.