I can't really vouch for the accuracy of this report, because it originates with Adam Schefter of ESPN...and, of course, Schefter's blog is behind a paywall (because he's so often right?).
But ProFootballWeekly is sourcing Schefter in its article, Report: Williams could follow Fisher.
This is the key sentence:
Fisher is considering taking either the Dolphins or Rams head coaching job, and it is believed Williams will follow him to either location.
"It is believed"? By whom? Based on what? There's little more than that single, bald assertion in this article...which is why I'm writing this as a FanPost instead of a FanShot: maybe it will get more views, and someone with an ESPN Insider Account can tell us if there is something more to the story than the idle speculation of one person.
In the meantime, said idle speculation opens up a very interesting question: should Gregg Williams go? Would the current defensive personnel do a better job in a different scheme...for instance, under Steve Spagnuolo? Because, all loyalty aside, the thought of this video game offense mated with a top 10 defense sends a tingle up my leg.