The question than will be how close we can come to the proprietary systems and which use-cases are low-key enough that their cutting edge new innovations don't make a difference.
I think the microcontroller space will be wholly owned by RISC-V in the long run. For cheap, commoditized stuff, open is better than closed for everyone. For the high performance stuff, the manufacturer still needs to protect their investment, especially because the will need to invest more and more for ever smaller gains.
Do you think that makes sense or am I phantasizing? :D