Well it also means that there will be many risc-v flavors since nobody like ARM controls it. So every chip can add a few instructions to differentiate themselv

Well it also means that there will be many risc-v flavors since nobody like ARM controls it. So every chip can add a few instructions to differentiate themselves. So if you spend a few $100M to a few $billion making a hot new risc-v core you are likely to add a few instructions for your intended use case/customer. The result will be significant fragmentation (which is already happening) which will make a mess of any OS and compiler support.