It's a big motivation to them on the rest of the matches, because it shows that they are capable of trashing any team if they're determined. Milan is picking form gradually after the sack of Fonseca, and I believe their new coach will lead the coach to a greater height. We might see more surprises from Milan as the season goes farther. I just hope they can struggle their way to finish on top on the table.
To finish at the top of the Serie A standings this season is still very difficult for Milan to achieve in the current conditions because Milan is far behind several teams in the top four of the standings, so it would be more logical for Milan to target the top four if Milan already has a new strategy and tactics through their current coach. Because in the remaining seasons that continue to run, it will not always be easy for Milan to compete in every match even though Milan has found a new performance that was lost when still coached by Fonseca.
Honestly, AC Milan hopes of finishing in the Champions League zone are very slim, because the points gap that has been formed is very wide. AC Milan must perform consistently until the end of the season and hope that Lazio, Juventus, Fiorentina and Bologna lose points, overtaking 4 teams at once, that is clearly not an easy job. In my opinion, the positions of Napoli, Atalanta and Inter Milan will not be disturbed, they seem to continue to be in the top three until the end of the season.
The change of manager has succeeded in having a significant impact on AC Milan, the success of winning the Italian Super Cup is an important capital to continue the struggle in Serie A and the Champions League. With the season still long, maybe AC Milan will get back the opportunities that have been lost, the most important thing is to get points in every match. If Rashford joins in the January transfer market, it will be a very good addition for AC Milan.