According to ESPN's Adam Schefter, there is a "belief from some around the league" that Donald will not play another down until his contract situation is resolved.
Donald is set to enter the final year of his contract, and if he does not report to the Rams at least 30 days before Week 1 of the 2018 regular season, he will become a restricted free agent next offseason rather than unrestricted, per Cameron DaSilva of USA Today.
Donald held out during training camp last season as well and missed the Rams' Week 1 game.
Despite that, he finished the campaign with 41 tackles, 11.0 sacks and five forced fumbles en route to being named Defensive Player of the Year. Donald has been named to the Pro Bowl in each of his four NFL seasons, and he is a three-time All-Pro First Team selection.
In 62 career regular-season games, the 2014 first-round pick out of the University of Pittsburgh has 39.0 sacks, making him one of the most productive defensive players in the NFL during that time.
Donald stands to land a record-breaking contract eventually, and L.A. would have a massive hole in the middle of its defense without him. The Rams did sign veteran Ndamukong Suh to play alongside Donald, but replacement options such as Dominique Easley and Omarius Bryant represent a significant drop-off.
Los Angeles orchestrated a surprising turnaround last season by going from 4-12 in 2016 to 11-5 in 2017, which was good enough to win the NFC West. The Rams are brimming with talent on both sides of the ball, but a Donald-less defense would represent a significant downgrade.