Apple has already won. Even if Intel catches up in efficiency, it doesn't matter. Even if they're 30% faster, it doesn't matter. Apple is in charge of their own destiny with Apple Silicon. That's invaluable.
It doesn’t make sense though because having your own architecture isn’t that useful if no one else wants to use it. The goal is to 10X your profits by licensing out your designs. Designing your own architecture is a 1X move if only you use it and that’s not counting the cost of maintenance and marketing.
Counterpoint: Apple has sunk an incredible amount of money into an architecture that provides very few tangible benefits to the consumer. It looks unlikely that they’ll ever recoup costs. They could have put that money toward their own fab and received infinite US government money instead.
Also, to suggest that Apple Silicon has very few tangible benefits is laughable. The power / performance are incredible, and the deep integration provides tons of optimizations that no other manufacturer can match. This ranges from seemingly simple things like M1 Macs waking up faster than you can open the lid, to long-term strategic advantages such as cross-compiling single binaries to both Mac OS and iOS, or adding custom silicon to cover software features with unprecedented efficiency with a guarantee that every single machine running it will have access to that hardware (over time).
They also threw out the ability to say "If your company/tasks don't work with MacOS, you can always dual-boot full-fat Windows."
They have to be betting that their platform is still big and compelling enough to keep bringing in users and developers to replace anything they lose to the x86-64 abandonment.
I tend to think that there's no real magic secret to ARM for low power, it's more that we've spent the last 20 years optimizing them for low-power devices while x86 was traditionally performance-at-all-cost.