I don't think we're anywhere near an "IT apocalypse". I think we're more likely to put a ton of machine learning engineers out of work long before companies start needing less help desk technicians and sysadmins. I think a lot of people have moved to the cloud only to discover they needed just as many people to help manage their cloud presence as they needed to manage their on-prem hardware.
The author does touch on this though by highlighting that you will need less and less people. As more services move into 'cloud' solutions it can free up time for those and they'll step into those spaces.
Yes, someone still needs to manage all of this but you need a lot less people. Or you ship these "trade jobs" to low cost areas like India.
The main thing moved to the cloud where I work leads us receiving and handling the same number of support tickets as when it was on-prem. The difference is, now some tickets we can't fix, and have to wait for the cloud provider. Service is worse, and it doesn't really save us any time.
A lot of cloud solutions offer an on-prem option. The tools are the same, it's just a matter of it running itself in the building or running itself somewhere else. A lot of times, running something on-prem means spinning up literally the same software you could have them host for you.
(Also: Windows Updates also aren't some crazy painful manual process that Intune fixed. You can just tell WSUS to approve everything automatically if you want, and just as similarly, you can manage Intune more granularly which takes up your IT staff's time and effort.)
If you're simply running EC2 instances with your same off the shelf software, you're not doing it right, but you'll still eliminate your entire datacenter physical facilities team and server install/rack & stack/replace failed disks team.
If you do it properly, it's incredible what you can do. I have a client with applications running in Ireland, Frankfurt, Singapore, Tokyo, and the US, totaling around 50 EC2 instances running containerized workloads that automatically heal, APIs that are accessible globally and won't go down unless 6 AWS regions simultaneously fail, about 30 static websites, DNS hosting for a dozen domains, monitoring, auditing, and log analytics for all of the above. I set it up in about 3 months as a single engineer and manage it all with about 8 hours a week of total effort. The cost to my client is basically the same as hiring a single senior engineer, but they're running infrastructure that would have taken a team of 3 shifts of IT professionals without the cloud.
Sure, some of them will still have positions the same or similar roles but there will be a crunch. The large outsources will be hit overseas (WiPro, Infosys, etc.) but it will also impact administrators at medium-large sized businesses in typical American Cities as Forrest mentioned. The worst part out of all of this is too many colleges and especially technical colleges still teaching networking, linux or windows administration as if they'll be able to have life long career. That is no longer true.
I don't want to imagine what it'll be like for those students who graduate, get good jobs (now), a mortgage and start to raise their family only to find themselves unemployed in the middle of their lives. I don't expect much sympathy from the largely meritocratic tech industry or anyone else.
As for myself, I already work for one of the big three and apart of many "cloud" migrations. I should be okay but at the same time I am somewhat conflicted. Am I going to need to go back to school for Computer Science and become an fully-fledged actual software developer? I mean, it's fine, there's still enough time (I don't think we will really feel the burn for at least another 4-6 years) but is it reasonable or realistic that everyone needs to be rockstar developer?