Core Four charter members Dan Girardi and Ryan Callahan are both one day closer to the end of their respective Rangers careers than they were on Wednesday. For without any progress made toward signing the marquee pair of pending free agents to contract extensions, management is devoting its attention to evaluating personnel who might become available in trades for the first-pair right defenseman and the captain in advance of Wednesday’s deadline. The uncertainty regarding the immediate and long-term fate of two of the four Rangers (plus Henrik Lundqvist and Marc Staal) who predated John Tortorella’s tour on Broadway represents the elephant in the room at the top of the 23-game stretch that commences Thursday night at the Garden against the Blackhawks. “For me, having our three New York Rangers going into their final year and having this situation in front of us has been a little bit challenging in the sense that those are the guys I’ve got to work with on a daily basis to make sure that when I’m not around, the right message and right behavior is there,” coach Alain Vigneault said, citing Callahan, Girardi and Lundqvist, whose own extension was not completed until late November.