C'mon, if anyone with the (legal, as well as technical) ability to do anything about it actually cared, AmigaOS would have been on ARM years ago, and now we'd all be happily using Raspberry Pis and Tinkerboards to run our systems.
Instead a few people choose to pay 20-100x more for boutique PowerPC systems.
A new ISA and ecosystem is all very nice, and RISC-V does appear to have some nice aspects indeed, but it's even more unlikely than ARM.
At least there is AROS and it's distributions.