WordPress 5.9 Full Site Editor – how does it impact Catch theme users

This is a question which would be applicable to ALL Catch theme users - possibly best addressed in a blog post. With the new 'full site editor' being introduced in Wordpress 5.9 (soon to be the new version) apparently the theme customiser - the way we have come to know it - is going to disappear. I've been reading a blog on another theme I use elsewhere (a block based theme) and it seems that those type of themes (and there are very few currently) will possibly work OK with the new editor. Or can readily be updated to do so. My personal view of the new full site editor is that it will drive 'average' users away from WP to squarespace and wix. It's much more complex / difficult to get one's head around that the tried and true current system. While it would obviously be possible to defer the 5,9 upgrade, at some point an upgrade is inevitable for security reasons. I run several sites with Catch Themes so this is a concern to me. What is the impact going to be for Catch Theme users please? Q: is there a way that an upgrade to 5.9 can be done but RETAINING the existing theme editor? Please advise.