IMO the only question is one of magnitude. Based on a cursory search it appears that adblock addons are used by anywhere between 20-45% of users across all browsers. Based on this I wouldn't be wildly shocked if Chrome sheds anywhere between 5-10% of its userbase almost overnight.

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.