People forget that the next step of Google will be the inconvenience. Meaning they'll make Firefox work badly on YouTube and other google websites. Have a video not play here, bad css layout there. Subtle stuff that will make people hate to use Firefox and because Google is dictating the Web standards, they will do so, in fact they actually already do. I've already had a few websites using some kind of PWA framework, that was horribly slow on Firefox compared to Chromium based browser.
Yeah I don't give a flying fuck how much inconveniences they create, I rather would push a hoop with a stick and never use YouTube or the Internet again then using chrome.
I've been using Firefox since its debut and I never had any issues, slowdowns or problems with it, same with DuckDuckGo so Google can stick it somewhere where the light doesn't shine.
FreeTube and other front-end replacements exist. Could they turn them off? Sure, with a bit of work.
Though so long as it is a public service (responds to the public) that does not require an account to watch videos ... they will only ever be able to annoy people. It's the same problem as piracy. It's a question of convenience, and if they make the main road a less good experience than the stripped down one... They're only hurting themselves.
If Google had half a brain, they would've embedded the ads in the video streams years ago. Instead, they "innovate" by making the entire internet worse.
(yes I know ublock blocks A LOT more than YouTube ads, and Google's revenue is all their ads, but YouTube is a perfect microcosm of why Google is the wrong company to solve this problem)