Anyone can design and sell little circuit blocks and on chip peripherals, even proprietary ones, for use on any chip.

What’s the likelihood of a dominant player emerging and implementing patented, proprietary RISC-V architecture changes which turn out to be necessary for high-performance? And if such a company gains sufficient market share, they could turn RISC-V into basically another x86-64 with many proprietary extensions. Sure, others could create their own RISC-V base processor - but if their performance is 500% lower than processors from the proprietary vendor who would purchase them?