Depending on what qualifies, ARM is there today, or will be soon if Apple has anything to say about it.
Apple's not really in the server market, though.
We are far past time for a successor. The x86 family has been an architectural mess since the 8086. It's time for someone to provide an alternative that motivates the market to dump the baggage and start with a clean slate focused on security and efficiency, as opposed to compatibility. Unfortunately, I see nothing on the horizon. Neither ARM nor RISC-V qualify in my view. We need something more radical that has dramatic advantages.
There is a lack of viable non x86-64 hardware. Most ARM server vendors have shutdown before they even released their hardware.
Sadly, POWER is going to get hurt in this Intel vs AMD price war. POWER 9 was until recently competitive in price/performance with high-end Xeons but, sadly, IBM would need to cut prices and that's something they are not going to do.