[smoldesu]

None of the manufacturers want in. x86 is unencumbered by licensing issues, and RISC-V is moving through evaluation like a jackrabbit on speed. Apple has incentive to make ARM chips - they're deep in bed with Softbank (ARM licenseholders) and were already designing their own ARM cores. Nvidia has a few industrial-application HPC ARM chips they manufacture, but have been noticeably quiet about ARM after the failed acquisition attempt. Intel is cashing in on fabless manufacturing and also not designing their own cores. AMD has it's headphones on and doesn't see the RISC truck barrelling down Main Street.

So... I would honestly be surprised if anyone tried, at this point. Most of the potential stakeholders don't seem super interested.