When Durham subpoenas them I believe they’ll have to comply or face potential jail time. They can invoke the 5th or just not remember but will be forced to show. This is what I’ve been waiting for. Now these felons will be under oath answering questions. They are very aware of the back stabbing tactics of their fellow coup plotters. There are no G Gordon Liddys in that crowd.
A lot of Trump's people have refused to comply with subpoenas and none of them are in jail yet. I don't see Brennan and Clapper coming voluntarily.