I agree that migrations to on-prem will happen - some already have and I read about one every couple of weeks. But I was thinking about another similarity to the mainframe environment recently. Back in 1980, when I first wrote Cobol on a mainframe, we'd submit our compile/link/run jobs, and wait for the printout with the results. Since this was a college environment, that wait was often a couple of hours, unless it was the end of a semester, in which case you may have to wait until the next day.
All my work is in the cloud these days, usually involving AWS services such as API Gateway, Lambda, DynamoDB, etc. I do consulting work for large corporations, and they usually have a build pipline. So when I'm working on code, I get compiler or linter errors locally, but then I have to give my code to the pipeline and let it build and deploy it. The wait is usually 15 to 30 minutes, but it can be longer if the pipeline has insufficient resources. I've waited hours for a deployment to complete on on occasion.
In the hey-days of the 90's and early 2000's, most things ran on your local workstation, which was a low-latency heaven. Unfortunately, I fear we've come full circle!