Brian Williams is definitely done, and I suspect NBC Nightly News will follow (or face a serious revamp). That said, it isn't the end of NBC or Comcast, and if Nightly News does remain, the next person to helm it will likely come from outside NBC's ranks (or be Rachel Maddow). This might also affect MSNBC, leading to a less liberal friendly program and sacking/reassignments for Al Sharpton, Lawrence O'Donnell and Rachel Maddow in favor of actually reporting news.
NBC's entertainment and sports divisions should face minimal if any effects.
Rachel Maddow isn't going to be sacked or demoted unless she commits a crime of some sort. She's definitely got some trust and appreciation within her workplace, seeing as she's been leading election night coverage ever since Olbermann got sacked.
