Do you have any actual sources that say Idzik was forced to keep Rex and doesn't have the option to fire him if he wants? People on this site speculated about it but I don't remember anything like that ever coming to light. Any GM to come in and fire a coach who's had recent post season success with the team and took MARK FRIGGIN SANCHEZ to an AFC title game twice is pretty dumb. Rex isn't a lame duck. That's just the media's latest catch phrase.
I think idzik is keeping his options open. When the first two picks of the draft happened, I was sure that he was stacking talent on defense in preparation for the eventual exit of Ryan in favor of an offensive HC. Now I think he has been making decisions for both cases.