Eh, RISC-V is gaining popularity in some areas but it's very far from settled. ARM is still extremely dominant and it's not likely to go away in the near future. For this class of processors specifically there are basically no competitive RISC-V versions available today, and I would not expect to see any for a few years.
I have used RISC-V professionally mainly because it was easier than worrying about licensing a different soft core for an FPGA. I have the same codebase running on an ARM cortex-m3. The RISC-V code uses far more flash and RAM (near 2x for code in flash and stack space in RAM), as far as I can tell because of awkward decisions made by the ISA (there are extensions which should improve this a little but they aren't available in the core I'm using). If it were a cost sensitive high volume application then ARM would win basically on that front alone, the license fees would be more than offset by the cost in hardware.
I have used RISC-V professionally mainly because it was easier than worrying about licensing a different soft core for an FPGA. I have the same codebase running on an ARM cortex-m3. The RISC-V code uses far more flash and RAM (near 2x for code in flash and stack space in RAM), as far as I can tell because of awkward decisions made by the ISA (there are extensions which should improve this a little but they aren't available in the core I'm using). If it were a cost sensitive high volume application then ARM would win basically on that front alone, the license fees would be more than offset by the cost in hardware.