Ibrahimovic only moved to AC Milan at the beginning of this season, following one year at Barcelona.
But reports have suggested his former Inter Milan coaches Jose Mourinho, now at Real, and Roberto Mancini, currently the Manchester City boss, are interested in renewing their professional association with the 29-year-old.
Raiola, though, says it's possible Ibrahimovic will finish his career at Milan.
"I'm not ruling out the possibility that Milan will be Ibrahimovic's last team," he told Roman radio station Radio Radio.
"I've been saying the same thing for 10 years. I can't rule out any team or any scenario because when we went to Barcelona we didn't go there to leave after only one year."
"The player wants to finish his career at Milan but I doubt that could happen."
"I'm not ruling out that another team with crazy ideas, not for this coming season but for 2012/13, could try to take him away from Milan."
"I don't know anything about interest from Mourinho. He hasn't called Milan or myself."
"Ibra is fundamental to a team that wants to win because he brings with him his quality as a player and his mental strength."
"These things are important for the changing room and both Mourinho and Mancini know that.
"But the fact is it must be (Real president) Florentino Perez who calls (Milan vice-president Adriano) Galliani to come to an agreement."
"But it seems impossible to me that Zlatan will change teams this year for two reasons: firstly Milan don't want to sell him and secondly because he doesn't want to leave, even if Mourinho calls."
"But if tomorrow Perez gives Galliani €100 million, then it's Galliani's problem. We'll only decide after that and the player always has the last word."