"Kaka has remained in our hearts because of the player and the man that he is," Berlusconi was quoted as saying on Milan's website on Tuesday.
"I don't rule out a hypothesis of that sort but it depends on the situation," the former Italian prime minister said.
Berlusconi's daughter Barbara, who oversees "special projects" at the Serie A club, and Milan vice president Adriano Galliani were "splendidly situated at their workdesks", he added cryptically.
The sales of top scorer Zlatan Ibrahimovic and classy defender Thiago Silva to Paris St Germain have angered Milan fans but Berlusconi said the club had to balance the books and would not be making any extravagant buys in the coming years.
Kaka, currently on a pre-season tour with Real in the United States, has shown flashes of brilliance since moving to La Liga for around 65 million euros.
However, the 30-year-old has been sidelined several times by injury and mainly played second fiddle to German international Mesut Ozil last season.
Real coach Jose Mourinho said on Friday Kaka's future was still up in the air but that he would be delighted if he stayed.
The 2007 World Player of the year has been linked in media reports with a move to cash-rich PSG, the Ligue 1 club coached by his former boss at Milan Carlo Ancelotti, as well as a loan deal back to Milan and a move to MLS side New York Red Bulls.