McCabe is still there because Trump still wants him there. Better question is what does Deep State have on Trump that keeps him from pulling the trigger.
Bingo! Trump has lost all interest in any matters involving the FBI, Obama, Clinton’s, etc... Sessions has done nothing to help Trump in any manner. Trump seems satisfied so that is how it will stay.
I believe you are correct in that Trump is being blackmailed(or sililar). It probably leads to his Taxes because the worthless IRS Director is still in place and no moves have been made to eliminate the guy.
It’s weird that this guy is still there .