Some of the most powerful processors in the world are RISC processors (ie, IBM's Power9), and what else is a RISC processor? ARM-based processors such as Apple's A-series.
There's no proof that says ARM will never be as performant as x86. Yes, most of the current widespread ARM implementations have been for mobile, but that doesn't preclude Apple from giving them more cores, more voltage, and active cooling. There are ARM-based servers in data centers getting deployed, that wouldn't happen if the performance just wasn't there.
Another reality, AMD came from way from behind on x86 and is now rivaling Intel's performance metrics, especially in performance per watt. Intel is not insurmountable, their process tech has been stagnant for awhile, and with enough innovation and funding, anything is possible.
We should be happy and hope that Intel is going to be put to the coals. Competition helps everyone.