Counsell isn't getting fired this season, he isn't being replaced in the offseason, and the Cubs won't likely consider firing him next season either.
But do we have any official info on how long Jed was extended for? If we assume this is the first year of a four year extension, he has 1-2 years before his seat gets really hot.
If the Cubs don't make a serious run at the World Series in the next few years, Jed isn't going to let Counsell get to the end of his deal. If Counsell plays out the string through 2028, the timing would be right for the Cubs to clean house and put a new person in charge to make the next manager hire.
All that to say, the timeline for Counsell to be fired is probably the end of NEXT season if the Cubs continue to underperform, or possibly the middle of the 2028 season.
But, if the current trend continues, someone else on the staff has to go, and soon.