One of the points the author makes is that "on-prem" these days often mean "someone else's AWS account". When we started about a year ago we suspected it would come up, but today it's turning into a most popular use case. And adopting something like Kubernetes in a smart way largely takes care of your concerns regarding agility.

Now, the story time!

When I was at Rackspace, I was trying to analyze the top reasons our startup customers would stop using some of our SaaS offerings. The most common one, unsurprisingly, was they'd run out of business. But another top one was "they got successful". As they got bigger and more successful (can't mention names) they'd bring more and more in-house, eventually getting to a point that the only products they were interested in were just servers and bandwidth.

So it depends. Some things just don't work well as SaaS, especially for customers with money who can't scale their IT fast enough.