The Legion of Boom has spearheaded one of the great defenses in NFL history, but it’s fair to wonder how much longer the trio of Earl Thomas, Richard Sherman and Kam Chancellor will remain together.

The crew has turned into the Legion of Drama over the past year. Last season, Chancellor created a big stir with a holdout that messed up the defense, and Thomas played tentatively for half the season as he returned from a bad shoulder injury.

The drama has continued this year, with Thomas injured again and talking retirement, Chancellor missing more time with injuries and Sherman sounding off every week about something.

Out for the season with a broken leg, Thomas has thrown out the idea of retirement a couple of times. No one believes he’s going to hang ’em up next year, but the fact that he is entertaining those thoughts during the dark days of his injury makes it worth asking: How much longer will he play?

His contract runs through 2018, and it wouldn’t be a surprise if he decided to retire after that — his ninth season.

Chancellor pouted about his contract last year but has not said a word this year. He seems likely to get an extension after this season, but it’s hard to see his body lasting more than maybe three years. He already is in his seventh season, and he hasn’t played a full year since 2013 — missing two games in 2014, five in 2015 and four this season. It is a very good bet that he won’t play a full season for the rest of his career.

An extension would be a big gamble on his health, but the Hawks seem very likely to do it because he is the heart and soul of the defense. When he talks, the players listen.

When Sherman talks, everyone listens. He was surprisingly quiet in 2015, a major flip from his loudmouth days the previous few years. But he hasn’t shut up this year, ripping the NFL every other week — either verbally or in writing — and going off on teammates and coaches.

His most recent in-game tirade was aimed at Darrell Bevell and the offense, making some wonder whether Sherman was creating a schism between the offense and defense. Carroll, obviously disappointed in the distraction, said it has been taken care of and “We’re fine here.” But if Sherman keeps it up, it is worth wondering whether Carroll and John Schneider will want to pay him another outrageous contract before his expires alongside Thomas’ in 2019.

Sherman is still at the top of his game, but 2018 will be his eighth season, and Schneider will have to decide at that point whether he is still worth $14 million (or more) per year.

The three Legionnaires are still big parts of Seattle’s stellar defense and should remain that way for the next couple of seasons. But we’re getting to the point where it’s fair to wonder how much longer the trio will be together.