Both ARM and RISC-V are Reduced Instruction Set Compute (RISC) instead of Complex Instruction Set Compute (CISC aka x86) architectures. So it's more about the tooling that makes one better than the other. And like all open source, the tooling will be better over time as people and organizations recognize they get more back out of contributing to open systems.
That's way too optimistic. If it's like "all open source," it will have some improvements, forks and then nothing. There are only so many people who can contribute to chip development, and they all have jobs.
