Revoking Certificate from InstaVR will not affect any of your existing/already published iOS packages on App Store.
Revoking Certificate from InstaVR will affect in your future packaging of iOS (App Store) for respective project(s). Please check following screenshot for warning displayed when click on Revoke button. It clearly says "Respective project(s) App Store packaging will be affected"
Note: Before revoke certificate from InstaVR please consult with our Support Team by clicking on Support/Chat button on InstaVR dashboard.