Ask HN: Is there still market potential for PKI?

10-15 years ago, it was predicted that PKI (public key infrastructure) would be ubiquitous and used everywhere. Now, fast-forward 15 years - the Internet has some large CA's that issue certificates for https websites (and an increase in private PKI deployments as well), but it appears to me like a "scaling-up" of the same types of use cases, not any particularly drastic growth into new applications.

I'm trying to get a sense of whether the market and use-cases are already saturated or whether there are still new opportunities for vendors who create PKI solutions. Are businesses & enterprises still investing heavily in PKI technology and infrastructure? If so, where are the biggest opportunities for growth? What are the biggest challenges that an organization faces when rolling out a PKI solution?

Note: I'm not a security expert by any means - I'm trying to do some research on the field and thought about asking the HN community for help understanding the market.

Thanks!