Actually I have a pretty good reason from the man himself, to suspect that he will not be returning.
I don't want to reveal how I know or turn this into a 'soprano' situation, but I'll try to illustrate.
Lets just pretend that Milloy had a personal website with a bunch of Bills logo's on it. Then he does away with that website and starts up a new one (about 5 or 6 weeks ago), yet this time there is no Bills logo, only an NFL logo.
Like I said, thats sort of an illustration of what I know. The reality is very similar. I realize it could mean absolutely nothing, but this went down right at the end of the regular season. Combine that with the fact that the team played like sh--, the D wasn't very good, coaching staff turnover, and he is a free agent, and it doesn't look so good.