Huntelaar should never go back to Serie A, italian style of playing does not suit him at all.
on top of that he is so good at the moment because Schalke are a very dynamic team with many creative players who run a lot to create space for him.
Raul, Farfan and Draxler are all capable of scoring and creating which puts a lot of pressure on their opponent´s defense which means that they can´t focus on Hunter alone and thus there is more space for the CF, which is fundamental for him because his technique is awful and he has a slow mind.
in comparison to that milan seems like the most static team in the world because our whole midfield is not comfortable while having the ball, they just want to give it to Ibra/Robi/SES and hope that they create something, needless to say that Huntelaar would never score a single goal with this lack of support.
In my opinion it was the right decision for us to sell him but Real really made a huge mistake there, i bet Huntelaar would score even more goals in la Liga.