Yes there are a lot of Wordpress installs, a lot of them perhaps never even updated. You can claim those as being loyal to Wordpress but if they just set it up and forget it then there’s probably no real loyalty to Automattic. If you have concerns about just setting up a site on a different platform outside of Automattic for whatever reason, why would you trust it any longer? Those people will move on to another just as easy to install cms. Wordpress hasn’t gotten easier to customize in the last x years since your 3.0 install or whatever.
Easy to install and forget isn’t a Wordpress exclusive idea. It perhaps has a lot of mind share, but this is the 2nd time Matt has taken drastic action. It’s now at historical precedent levels.
To recreate the site in another CMS will cost hundreds of more dollars, at minimum, (probably thousands, realistically) and even then: what CMS are they switching to that's easier to use and has as wide a variety of plugins as WordPress? Because I'm not sure that CMS exists.
So the conclusion is: why switch? WordPress is perfectly fine for these people.