Most of the "Services" are the App Store and iCloud and AppleCare, so it's still directly tied to market share of the iPhone. If iPhone sales drop 20%, "Services" will drop 15% (with some amount of time lag / smoothing)

iCloud (and the Mac) App Store, AppleCare are Mac products as well. But to your point, sure, Mac sales are a fraction of the phone's—the latter's loss would be devastating for Apple and for services.

It's too bad the world has moved on as it has. I liked Apple a lot when they were just a computer company.