AMD under Lisa Su has really righted the ship. As of today, AMD's 7nm CPUs have pretty much overtaken Intel's performance crown, straight up, not just on price
erformance. I don't expect Intel to be able to even begin catching up until they move to 7nm (currently expected to happen in 2021), but who knows where AMD will be by that point.
I believe that the rumors of Apple consideration of moving to their own CPUs for use in Macs were at least partially due to Intel's lack of true advancements. Looking at Intel's best consumer level offerings today, we have the i9-9900KS CPU and refreshed Coffee Lake architecture. These are nothing more than extremely minor evolutionary updates to Skylake which debuted over 4 years ago.
However, I don't know if whatever Apple has developed can compete with AMD's current offerings. Those Threadrippers are absolute beasts! Shifting macOS to AMD would be much easier and would maintain virtualization compatibility for those users who use it. Making macOS run on AMD has already been accomplished with the stock kernel (albeit with a fair number of kernel patches in Clover).
From a business perspective, it would allow Apple to lower prices and increase sales numbers without sacrificing margins. It makes too much sense and I'm sure stock holders will love it. Going to AMD and not lowering prices would be a huge mistake.