4:52pm: When speaking after the game, Colts head coach Shane Steichen said (via James Boyd of The Athletic) the injury “could” be season-ending but did not confirm if the worst-case scenario has taken place. On that note, Pro Football Talk’s Mike Florio also reports a tear is the situation in this case. Once testing ocurs, it will certainly come as no surprise if/when that diagnosis is confirmed.
2:37pm: Things have gone from bad to worse for Daniel Jones and the Colts. Indianapolis’ starting quarterback suffered a non-contact injury (video link) during the team’s game against the Jaguars. 
Jones’ reaction has led to concerns he suffered a major injury. Indeed, Outkick’s Armando Salguero reports a tear is feared to have occurred. In any event, Jones has been ruled out for the remainder of the game.
In recent weeks, the free agent addition has been dealing with a fibula injury which was reported to be a fracture. No confirmation emerged on that front, but Jones’ health and mobility was already a talking point leading up to Sunday. In the event of something like a calf strain, missed time would be in store. Of course, an Achilles tear would represent the worst-case scenario and end his season.
After seeing his Giants tenure end and departing the Vikings on the open market, Jones faced tempered expectations for 2025. The former No. 6 pick did not surprise many by winning a competition with Anthony Richardson given the fact much of his $14MM in compensation was guaranteed in full. Nevertheless, Jones’ strong start helped power to the Colts to a 7-1 record. Doing so set him up for a major raise on a second Colts contract or one worked out in free agency this spring.
Indianapolis parted with a pair of first-round picks at the trade deadline to acquire Sauce Gardner. That signaled a desire to commit to Jones and the other members of the Colts’ core. An offer on a long-term pact is expected, although no talks on that front have taken place yet. Needless to say, a major Jones injury would make a massive impact on the financial situation in this case.
With Richardson still on injured reserve, rookie Riley Leonard has taken over QB duties for the Colts. The sixth-rounder had only made one appearance prior to today, making two pass attempts. For now, at least, it will be Leonard counted on to lead the team’s offense. If that remains the case down the stretch, Indianapolis’ chances of winning a division it was once firmly in control of will be dealt a massive blow.
The Colts entered today sitting at 8-4 after losing three of their last four games. The team’s outlook will hinge in very large part on Jones’ diagnosis. Likewise, his future will be greatly impacted by any significant injury if one is to be confirmed by further testing.