"Ryan Shazier won't play in 2018," Colbert said. "He knows that, and we know that. We're going to continue to support him in his recovery."
Shazier -- who suffered a severe spine injury in December -- will remain a valuable part of the team and will be placed on an exemption list.
Colbert said it will be a challenge because the Steelers will be at 89 players, but "fortunately for Ryan, he's covered in that manner."
"He will be part of our team officially, and really unofficially because he's still with us day-to-day as he rehabs," Colbert said. "He involves himself in team issues so he can be a formidable member in 2018."
Shazier is due $8.7 million for the fifth-year option the team picked up last April. He's not under contract for 2019.
Shazier underwent spinal stabilization surgery Dec. 6 and has graduated to outpatient treatment. Questions persisted about Shazier's ability to move his legs shortly after the injury, but he is now standing on his own accord and making steady progress.
This offseason, Shazier has been working out at the team facility and sitting in on scouting meetings. Speaking on teammate Roosevelt Nix's podcast last week, Shazier outlined plans to play again.
"I've gotta get back, bro," Shazier said.