Le'Veon Bell and the Pittsburgh Steelers were unable to agree upon a long-term deal before Monday's deadline.
Bell's agent predicts this will likely be his final season with the Steelers.
"His intention was to retire as a Steeler," Adisa Bakari told ESPN's Adam Schefter. "But now that there's no deal, the practical reality is, this now likely will be Le'Veon's last season as a Steeler."
Bell will play on the franchise tag for the second consecutive year barring an unforeseen development. He tweeted after Monday's deadline passed that "2018 will be my best season to date."
Bell always knew he could play out two franchise tags worth a combined $26.62 million and have a chance at true free agency as a 27-year-old in 2019, setting the stage for peers Todd Gurley and Ezekiel Elliott in future years.
Bell has used boxing and a vegan diet this offseason to stay in shape, holding off from most football exercises to keep his knees fresh.