Jackson leads the Colts with 78 combined tackles. With four games remaining in the regular season, he'd be eligible to return for the playoffs should the Colts qualify. Otherwise, his next appearance on the field will be in the 2017 season.
Indianapolis may have faced a stretch without the 33-year-old regardless of his suspension. Colts head coach Chuck Pagano confirmed Monday night Jackson suffered a concussion in the team's 41-10 win over the New York Jets, and he's in the NFL's concussion protocol, per Indy Sports Central's Mike Chappell.
Jackson's suspension comes at a terrible time for the Colts, who are in a three-way tie atop the AFC South with a 6-6 record.
Indianapolis will likely count on Antonio Morrison to fill in for Jackson at inside linebacker in the final four games. Morrison, a fourth-round pick in the 2016 draft, has 20 combined tackles in 12 games as a rookie.
That will put a lot of pressure on the 22-year-old given the stakes of the next month. The silver lining is that the Colts have an opportunity to see whether Morrison can be a long-term replacement for Jackson.
Jackson has one year left on his deal with the team, and Indianapolis would save $5.5 million against the salary cap with $250,000 in dead money if it cuts the veteran in the offseason, according to Over the Cap. Should he play well to close out the season, Morrison may have the inside track for the starting job in 2017.