Cohen has plead guilty and there would be nobody other than Trump for Pecker to testify against in return for federal immunity.

The only conclusion is they plan on charging Trump. Pecker's testimony backs a conspiracy charge against Trump.

Its the "trump card". Its why he has lost it. Its why Rudy & Jay have shifted to "the investigation needs to end now". Mueller and the SDNY have Cohen's records and now his accountant and any State law violations will go to NYAG's office. Its probably why Preet isn't running for NYAG(doesn't want to be the one to prosecute Trump). Donald can't pardon anyone for State crimes and nobody outside the NY Governor can pardon him and his family for State crimes. This is the end game and he knows he is stuck. I would not be surprised if there are State indictments sealed as we speak waiting for the second he is no longer President...