If they start selling your data, they'll quickly eliminate the very market share that gives them such power. And why would they want to give up that data anyway? Better to use it themselves. A lot of people will accept the data collection as long as it doesn't go to third-party companies, we have ample evidence for that already.
No they absolutely will not. 99% of Apple users do not care about privacy. And when Apple does this, those users will find excuses to why it's okay.
https://arstechnica.com/gadgets/2021/05/96-of-us-users-opt-o...
If iPhone started reneging on privacy guarantees, I for one would switch to a dumb feature phone the same day.
The fact that Facebook got decimated by the controls added indicate the level of concern people have when offered a choice.
The fact that you would even consider this means you are a part of that 1%.