They are massive on paper and I'm sure AMD will have a hard time matching that. AMD's advantage will be Zen3 + their new cards as package.
Apple's ultimate goal is to completely seal themselves off hardware-wise - they will slowly start dropping AMD in the low energy space 1st and in 5-7 years aim to move the entire line up to Apple silicon both CPU and graphics. They will still have a very hard time competing with Nvidia, but I don't think their goal is do that. I have no idea what personal animosity exists between the two companies / CEOs though, but clearly they need AMD still, but once ready will drop both and achieve their pipe dream from the 80s/90s of having again a vertically integrated proprietary stack. And I gotta say I can't fault them for that - it works very well as a model when you execute it the way they do.