Do you mean comeback to the top 5 in EPL standings? You're right, it seems very difficult to return to the top 5 because Man United performs very unstable and the point gap with Tottenham in 5th is quite large. If there is no change with Man United, I think Man United probably finishes in the 6th place for this season. However, it won't be easy, West Ham and Brighton are competing for the same position. Man United also must be aware that West Ham and Brighton aren't weak teams.
This season, it is difficult for Man United to return to the top five, especially since it is impossible to reach the top four with points behind and Man United's unstable performance is getting worse. However, Erik Tan Hag still has time to improve it in the second half of the season. Erik Tan Hag has indeed failed to make Man United improve, but he must prove he can handle it in the remainder of this season. Man United must catch up with 8 points behind Totteham.
Yes, it is time to fire Ten Hag. After this season is over, I am sure Man United probably fires Teh Hag. He failed to improve Man United, he also made some problems with players. It is not a wise decision to keep Ten Hag in the club if he often makes problems.
I don't think dismissal is a solution, how many times has Man United fired a coach? I'll stick with Ten Hag for now. He is actually a brilliant footballer coach, who has faced some difficult problems off the field and many injuries. He deserves a third season under a more stable structure.