Hi @pixel,
actually the current development version has already moved on to version 11. 8.7.x is still the current version for customers.
As part of “Kopano One” we are currently rolling out version 9 of Kopano Groupware. The next step in this project is to design containers that can be used in Kubernetes environments and app stores such as Univention, Synology and Cloudron. Since Kopano One requires a license key this will however not be released as an update, but rather a new app.
Cannot give an ETA on this at the moment.