On the one hand, Apple has some potential ad business ceiling.
That ceiling number varies according to how well they can target.
On the other hand, Apple has some amount of iPhone et al. sales that occur because they respect privacy.
Eventually, increasing the former will decrease the latter. I think Android shows us the link is weak (because most people don't care, if tracking is hidden), but it exists.
My impression would be that right now, Apple is targeting far less than their customers would allow (while still buying equivalent amounts of hardware).
The issue is +5 or +10 years, when Apple has a few bad product launches and needs to find a revenue stream, and selling a piece of their privacy soul to juice revenue is an easy bargain to make.
Google's central evil was allowing ad revenue to metastasize and dominate the company, which in turn meant that ad execs have more pull than is healthy.
