"What our team will be at training camp? I don't know what it will be," Colbert said.
Colbert also said the team hasn't yet made a decision about veteran wide receiver Hines Ward, who has two years and $8 million remaining on his contract, although there have been "internal discussions."
Ward, 35, has publicly said he wants to play out the rest of his career in Pittsburgh despite his diminished role behind Mike Wallace, Antonio Brown and Emmanuel Sanders. NFL Network insider Jason La Canfora cited sources in reporting last week that the Steelers are likely to cut Ward, who became the eighth player in NFL history to reach 1,000 career receptions.
One of the players who will return, eventually, is running back Rashard Mendenhall. Colbert said Monday that Mendenhall likely will begin next season on the physically unable to perform list after tearing the anterior cruciate ligament in his right knee during the regular-season finale against the Cleveland Browns.
Even while expecting to be without Mendenhall, who had 228 carries for 928 yards and nine touchdowns last season, Colbert doesn't consider finding help at running back an offseason priority for the Steelers. He said Isaac Redman has "established himself as an NFL running back," according to the Post-Gazette, and mentioned rookies John Clay and Baron Batch and second-year pro Jonathan Dwyer as possibilities at the position.
The Associated Press contributed to this report.