Google's core revenue stream doesn't rely on IDFA. Many 3rd party advertising companies and apps do rely on IDFA. Apple's move helps Google.
Removing of IDFA should close the gap between big players like Google, Facebook etc vs others.
Then how would third parties with no access to first party data compete when there's no more third party data would be something I'm curious for you to explain.
I think after removal of IDFA, smaller ad networks will steal some of big players mobile market share. And mobile advertising will not move to search based advertisement as much as you think. Maybe some revenue will shift there, but I think lose on mobile side will be bigger.
Google’s ability to protect its core revenue stream is squarely in the “not impacted” category when it comes to Apple's IDFA move.