They still have chance because the season is long and it has yet went half of a season. However they must improve themselves a lot to compete with other clubs. The rises of Newcastle United, Arsenal and Tottenham make competition for top four is very challenging and Manchester United will fail in this race if they make too many mistakes during this season.
Sacking Ten Hag won't help them as they already sacked many coaches previously. Sacking Ten Hag, hiring a new coach, don't change their transfer strategy, they will fail again.
Manchester united have had many set backs that's caused them to drop in form especially the injury crisis that occurring in th club they've recorded about 19 injury cases this season but that's not an excuse cause if they had strengthen their squad depth very well it would've helped them alot,alot of mediocre team are beginning to pick up and are investing on their team to get better performance, however Manchester United needs to sit up and stop leaving in past glory, they need to put heads together and work as a team to start getting good performance.
Sacking Ten Hag won't change anything but rather would even cause more problems for the team cause the new coach might even find it more difficult to work under the glaziers that are only interested in the financial benefits they're getting from the club instead of making investments to help it grow.