RISC-V is currently already being used in MCUs such as the popular ESP32 line. So I’d say it’s looking pretty good for RISC-V. Instruction sets don’t really matter in the end though, it’s just licensing for the producer to deal with. It’s not like you’ll be able to make a CPU or even something on the level of old 8-bit MCUs at home any time soon and RISC-V IC designs are typically proprietary too.