When do they have their License Renewal?
To wit, the FCC licenses are not "owned" by ABC/NBC/CBS. Rather, they are permits that allow them to broadcast over delineated portions of the air waves owned by the American people. However, in order to enjoy the rights & privileges associated with their exclusive use, they must conform to certain rules of conduct & behavior.
It's important to note that the primary role of the FCC is to ensure protection of assets/resources held in public trust. (Actually, this may seem a bit redundant, but that's the defined role of all gov't agencies.) By firmly associating the MSM with propaganda and other patterns of untruthful reporting, Trump is establishing the framework for suspending and/or revoking their broadcast licenses since they are, by definition, violating their terms of the agreements.
As we all know, the 1A guarantees freedom of speech, association, religion and press. However, it does not necessarily mean that a self-described group of 'journalists' has exclusive access to the WH, Trump and other members of gov't. If/when Trump combines revocation of press credentials along with FCC suspensions, we will see the collective collapse of many a media company.