>>Their influence and credibility are gone or very greatly diminished<<
I certainly wish this was so, but I know many people of various education levels who are addicted to the mainstream media because they simply must have confirmation of their own false beliefs by what they view as “authoritative” sources.
Your evidence is anecdotal. Meanwhile surveys from established, credible sources say otherwise. Where trust has been lost is among even minded reasonable people. Those on the fringes will only believe what they want.
Btw, this an NPR POLL reported by FNC.