With Redhat/Centos getting away from brtfs will rockstor be moving to VDO Vitrual Data Optimizer for doing compression , deduplication and thin provisioning?
No, Rockstor is built around the concept of BTRFS.
The development team are currently in the process of making Rockstor compatible with OpenSUSE instead, while (for the foreseeable future) maintaining compatability with CentOS.