Wish him the best but he will realize that life in a broken club is very different than at a well oiled machine like Juve and Madrid.
He spent two years here and to spearhead the attack of a fallen European giant in a League he is familiar with, at a time where they are supposed to launch a massive rebuilding project is a good opportunity to create history, get guaranteed game time and good money.
I would still take Chelsea imo. It will be a successful team, good money, great exposure and EPL football will suit him as well. He can start winning trophies immediately there and cement his place in the Chelsea frontline for years. Milan will take years to rebuild.