Developers are the core of any system. Once they move on, it's game over. What Wordpress.org did sent a clear message to any developer who makes a living on WordPress or a plugin - we can take your plugin and revenue any time we want. No rational person will continue to invest their time in such an ecosystem, no matter its "maturity". It clearly is not mature enough.
I would keep an eye on PayloadCMS or Ghost. Those, among others, are the future, IMO.
There are many good CMSs, no doubt. But Wordpress is the de-facto standard, every theme has first class support for Wordpress. And every thing on the web has a Wordpress plugin.
It’s not rocket science to learn another CMS, but many people are deeply invested into Wordpress and it would take a lot of money and effort to switch.
Even if the popularity of Wordpress decreases now, Wordpress (or a compatible fork) are going to be relevant for at least another decade.
The Wordpress license GPL/Copyleft makes forks rather easy.
I would keep an eye on PayloadCMS or Ghost. Those, among others, are the future, IMO.