In reply to Andre.

of when they are confident enough to cancel without the need for updates or support.

With current WordPress release schedule including many Gutenberg related changes and many additional ideas and here and there even a few fixes on regular/rapid basis, it is not possible to simply cancel theme-support any longer.

The only "solution" is not updating WordPress core, which can be seen at a lot of a bit more complex sites already. People stop updating because their "ready" and well-paid site simply broke after some update and they had to hire the dev a second time to get it working again. Those people "learn their lesson" quickly, no updates = no extra costs.

Also quite some plugins stopped development/compatibility notice after 5.0.x or a little later, unfortunately plugin repository has no real working search for those features/requirements, would be interesting to have more insight there.