Club president Joe Banner will have input. General manager Howie Roseman will have a say. Christina Lurie and the men who own pieces of the team will be consulted. Reid himself could stun everyone by choosing to move on, citing burnout or opting to pursue some other opportunity.
Ultimately, though, it comes down to what Lurie thinks. To be specific, it really comes down to how the owner answers three questions:
What did Lurie really think when Reid told him he wanted to promote Castillo from offensive line coach to defensive coordinator?
Lurie has given Reid endless amounts of rope during his 13-year tenure. There has been none of the Ray Rhodes-era griping about being denied the talent to win, because Reid has had a huge say, usually final say, on all moves. That means players, coaches, and personnel staff.
When Reid made the jaw-dropping decision to ignore a league full of conventional candidates to go with Castillo, most people thought he had finally tied that rope into a noose. If Castillo excelled, Reid might use it to lasso a Lombardi Trophy. If not, the trap door would surely spring open.
If Lurie shared that thinking, then Reid has to be in trouble. He has just wasted three years because he refused to look beyond his own meeting room to find a replacement for the late Jim Johnson. Does Lurie really allow Reid to decide who coaches the defense next season? And can Reid accept having his most important assistant forced on him?
If Lurie, by virtue of breathing the same air within the NovaCare bubble, thought the Castillo idea sounded just grand, then he has to take that into account. If he was fully onboard, then he has to address his own flawed judgment before he can blame Reid.
Does Lurie really think Michael Vick is going to win a Super Bowl?
If the answer is yes, then it makes sense to bring Reid back to coach Vick for at least one more season.
If not - and given Vick's performance, his injuries, and the level at which quarterbacks young (Cam Newton, Andy Dalton) and not-so-young (Aaron Rodgers, Tom Brady, Drew Brees) are playing, one must wonder - then it gets interesting. With a relatively high pick in a potentially QB-rich draft, the Eagles have to think about getting their quarterback of the future. If they do, then why have Reid and Marty Mornhinweg coach him for what could be one lame-duck season?
Back in 1999, the plan was to bring in a bright young head coach and a franchise quarterback and let them grow together. For six years, that worked pretty well.
One theory holds that since Vick's contract commits the Eagles to him through next season, they have to give Reid and Mornhinweg that season, too. That seems kind of backward. The long-term deal with Vick, which came on the heels of time and money squandered on the Kevin Kolb non-era, may well turn out to be an expensive mistake. How does it make sense to compound that mistake by rewarding the coach who made it?
Finally, does Lurie share the fear of fans who think changing coaches means a return to Kotitean futility?
For 13 years, Reid has mostly kept the Eagles competitive and in playoff contention. He has won more games than any other coach in team history. All true.
But in the 12 previous years, 10 other head coaches have won Super Bowls. That's nearly one-third of the league. Ten of the 12 Super Bowls have been won by head coaches who were hired the same year as Reid or afterward.
Reid is, without question, a very good head coach. But the idea that he's the only one capable of winning here flies in the face of all available evidence.
Lurie likes to say he is never "risk-adverse" in making decisions. Does he see changing coaches as a risk? How about not changing them?
Everyone has an opinion. Only Lurie's matters.
Contact columnist Phil Sheridan at 215-854-2844, firstname.lastname@example.org, or @Sheridanscribe on Twitter. Read his blog, "Philabuster," at www.philly.com/philabuster
Read his columns at www.philly.com/philsheridan