If you look at all the successful QB's in the last 15 or so years, its hard to find one that struggled like this in year 3. The famous early struggling QB turn great is Drew Brees. He had a bad year 3 and thats why they drafted Rivers., but that was only his 2nd season starting so not really the same.
Alex Smith had a rough start, in and out due to performance and injury, then went to KC and had some success but Alex Smith was not prolific. He was a 20TD, 3500 yard passer, game manager QB in KC. You can see what that offense really does with a good QB.
Stafford and Goff struggled first year starting then improved. Otherwise, Wilson, Mahomes, Watson, Brady, Luck, Dak, Rodgers, Ryan , Carr, Wentz.. now Jackson. All good year 1. Can't find any great QB's that were totally inept in their 3rd year, so chances he can be saved are highly unlikely.
Some are comparing him to Bortles. His third year was 4400 yards, 35TDs so Trubisky isn't remotely close. Others say Tannehill but Tannehill was 4000 yards ,27TD, 12INT in his 3rd season and followe that up with another 4000 yard season with a 2 to 1 ratio. So yeah.. umm Trubisky isn't even as good as these guys.
Trubisky's career right now. Bad year 1, slightly better year 2 on good defensive team that made playoffs. Then year 3 took a big step back.
Most likely career track = Christian Ponder