If you force Apple to open up iOS then Chrome just takes it over and Safari will take such a hit that Apple will probably have to kill it. Then Google will own 99% of the portal to the web.
I think I'm arguing with a bunch of Libertarians though who think that an unregulated market is some kind of magic sauce that will conjure up a Chrome competitor out of thin air, and not a recipe for monopolization.
Because Chrome will instantly start to out compete it. And once Safari is pushed down below 25% share on iOS then sites will feel more and more free to avoid testing on Safari and push users towards just using Chrome. Not having two different engines to have to test against means that even more the web becomes something that works on Chromium by default and is totally broken on Gecko. That makes FF even worse, and Google will totally control Chromium and the engine that browsers like Edge and Brave work on top of and will be able to dictate (in the "dictator" sense of that word) what the engine does (and while they might be somewhat responsive to Microsoft, they won't be to Brave). And we already won the battle to keep Windows from tying the browser to the O/S on windows and watched while we lost the war and Google completely took the engine over. Cracking open iOS is going to let Google take over that platform as well, it isn't going to make life any better for Gecko or any other alternative engine.
Let Apple permit the use of OSS browsers with their native rendering engines - problem solved. Will they do this ? I guess not because it means their native app development is threatened.
1) Firefox cannot compete against Google endless resources m. Google will win, not a matter of it but will.
2) The time it takes to decouple chrome from google will be too long. It may just kill Firefox before any action can really be done.