No consumer refines their own petroleum or makes their own steel these days, except maybe as a hobby. Similarly I don't think the market share of consumers who host their own email, git servers or payment infrastructure will ever rise again.
Every IT shop I've ever interacted with has a sizable on-prem footprint. And an even larger self-managed footprint if we include things that are run in the cloud but are managed by the IT shop itself (i.e. Red Hat OpenShift on AWS, HashiCorp Vault in Azure, GitLab in Alibaba, etc). So I think we've yet to see the initial demise of that paradigm.
Even if the trend is that most Enterprises are moving towards SaaS and PaaS products, I think we still have a long way to go until the majority of IT infrastructure is managed by a third-party.
If you're running 10,000 machines then you divide your management costs across them and treat them as cattle and end up spending (not real numbers, obviously) 0.02 person-days-per-month-per-machine or whatever on managing them. But that doesn't mean that with the same tooling you could run just one machine with just 0.02 person-days-per-month, because a lot of the benefit you're getting from scale is the ability to make one decision and do something to all 10,000 machines at once, and it's the decision that takes time and effort.
Not even in the least - they treat them like cattle. If data center scale tools were easier to use for the average engineer - the gap between managed and self-hosted would start to close. Obviously, software, tooling, process, scale: there are plenty of huge challenges to making self-hosting viable. Personally, I see it as far more doable and less radical than trying to distribute the internet in any other fashion (blockchain or otherwise).