Actually, the Corona render support for Archicad was more a victim to the COVID pandemic lockdowns and the staff shortages it caused in a lot of industries, rather than to the buyout by Chaosgroup.
The Corona guys were already having a difficult time getting developers to work on the project and were under-staffed, and then the lockdown and the forced work-from-home situation made things worse and they had to cancel the project.
You make it sound like this was all Autodesk's doing when they have nothing to do with running that company.
You forget that Vray is also available for Rhino, Sketchup and Cinema4D - none of which are Autodesk-related products.
If the aim was to kill support for non-Autodesk related Vray or Corona plugins then wouldn't those also have been eliminated?