I believe it won't happen...but if it does (in the summer), we can enforce a bidding war and I'm sure we can get over 30 mil for Pato (around 40-50), he's 22, has rather good press around the world, and I do believe he has potential, I just don't think that potential will show up at Milan. In fact, I'm sure we can get more money.
Now what are we going to do with that Pato money? Well yeah part of that money won't be invested on new signings, lets be honest here. The thing we can do is in a bidding war, try to get a player in exchange + money (midfielder + money, and we can use part of that money on a well it seems LB, but dunno maybe things will change by June), that would be the smartest thing, cause even if the rest of the money won't be invested on another signing at least we got a player we need.
Now, obviously I expect that before (that's kinda hopeful-naive, considering the precedents) we sell Pato we have his replacement in the team, weather its Tevez or someone else, so that we can avoid the Richy Oliveiras-Huntelaar type of panic buys.