Will this even be an issue when we have CPUs with hundreds/thousands of cores that can just sandbox processes to their own set of cores/cache with exclusive unshared memory?
Yes, there are definitely workloads that will benefit from better hardware, e.g. video transcoding or pure number crunching, but i would contend that most websites, databasing, ci, &c could be done on something like a pi replacing a vm or 3 (of the same customer).
I don't have hard numbers, but I wouldn't have thought it would be all that dramatic.
As for price competitiveness, some customers might be ok with paying for the increased security.