I don't see why offloading Pirlo would have anything to with re-acquiring Kaka. Kaka is a very attacking midfielder, personally I would call him a secondary striker/deep lying forward.
I think its rather likely that AC Milan will move to get him back. But then again, they will need a lot of midfielders soon, as van Bommel, Ambrosini, Pirlo and Gattuso is at their careers end. Flamini has not been what he looked to become his final season in Arsenal, Prince Boateng seems to be a hit... But all in all, the priority needs to be strengthening, and perhaps start to replace some of those midfielders. Midfielders is key acquirement. But what Milan do have is forwards with "midfield skills". For example both Cassano and Ibrahimovic are great playmakers next to a danger in front of goal. I think Kaka would fit fine in their current formation, but with Robinho, Cassano, Pato, Inzaghi and Zlatan Ibrahimovic. They still own Barriello too. I just cannot see Kaka being a priority... Then again Zlatan Ibrahimovic and Alexandre Pato does not seem to be too fond of each-other. They did not pass to each-other the past couple of matches. Zlatan seems to be Allegri's favorite, while Pato has hit the sweet notes with Barbara Berlusconi whom just got employed in the board or something. Zlatan has a bit of a ego so if the situation there escalates it might be a interesting drama. They need midfielders though, that should be the first priority this summer.
There is another Italian giant that can move for Kaka too though. Juventus are no where near the top of Italy and a signing like Kaka would help out - they certainly have the funds. He can go both to Inter and Milan as well of course. He went for £60m, and it will be interesting to see how far he drops. There are not many English clubs that will do a £30m signing for Kaka... Manchester City is probably the only one. Dream scenario would be that Tevez wants to a Spanish speaking country and some kind of swap deal. That would be in Real Madrid's favor.