On the other hand Apple might happily accept those payments for now, but realize that they won't keep coming forever.
It's quite possible that DOJ antitrust action would prevent Google from paying to be a preferred search engine in the future. Once Google isn't paying you, why not provide your own search engine (and cut Google off from that valuable data stream)?
Or Google turns sates evidence and blames that nasty monopolist Apple for extracting the Vig from them, and suggests that Apple must have a ballot in Mac OS and IOS a bit like MS
Given that Google also pays Mozilla about the same amount, it would be hard to prove that Apple's "extracting" it from them. Google very much wants to be able to pay all the browser makers to be the search engine of choice. Nobody has to extract anything from them.
Absolutely, but I really doubt that Apple will just shrug its shoulders about the lost profits and throw in an ad-free search engine for the price an iPhone.
My prediction is that they will try to monetise this somehow. And the most likely way to do this is via some privacy friendly advertising model (or an ad/subscription hybrid). They're already doing it with Apple News.