I just remembered that Kjaer just left so I think this transfer is very connected to Milan. There is no reason for Milan not to sign Mats Hummels because of course they have monitored his performance during this season and because of that they are starting to solidify their intention to sign him.
Apart from that, currently Milan has a new coach, namely Fonseca, and I think his involvement in determining the new players for next season is also very important. What is clear is that Milan must move quickly if they don't want to be overtaken by Juventus or Roma because these two teams will definitely make offers that are no less attractive, whether in terms of starting positions or fairly decent salaries.
This season Milan lost 3 important pillars that made them able to compete in Serie A so far, Giroud has officially left for the American MLS while Pioli who is the Milan coach also officially separated from Milan after he was fired this season, while Kjaer of course cannot doubt his capacity and also his contribution so far in maintaining Milan's defense, Kjaer, who has been playing for Milan since 2020, of course continues to be Milan mainstay so far, Kjaer, who is currently a free transfer player, has not decided where he will continue his career.
Mat hummels is certainly one of the right alternatives for milan to replace the position left by the current kjaer, especially since the situation of Mat Hummels is no longer comfortable in Dortmund at the moment, Mat Hummels decision to leave certainly provides an opportunity for Milan to be able to recruit him next season, in addition to focusing on defenders, milan should also focus on finding another striker to replace the position left by Giroud at this time.