With the introduction of Reactive, it is not possible any more to get user session data. That is probably a technical choice or limitation. The service center application now manages the user session and its data are not accessible. 

It would be great if an action is added (to service center) to terminate a user session by the user id.

This feature is really useful and will help in managing users and do auto logouts. Now we have to keep a shadow session management on top of OS to do such things.