The biggest investment we will have to make is in the attacking department. Sadly, those players are always the most expensive and we don't have much money.
IMO we should confirm only 3 players upfront: Ronaldo, Dybala and Kulu.
Bernardeschi, Douglas Cost and Higuain should go (either they are not good enough, always injured, or mental midgets). As much as Douglas can change a game, we need to move on.
So in my book we need 3-4 players upfront. Milik might be one of them. I would gladly take him over Higuain as bench option. Also strong player like Zapata would be ideal for Serie A, maybe even CL. You need different options. When clubs park the bus, you need a solution and a strong player in the box can help a lot. I also have a feeling he could work well with Dybala and Ronaldo.
I just hope we will sign players that Pirlo approves. You can't just sign 7-8 players that were cheap or available and hope he can make miracles of combining a first 11. And we were doing exactly this for past 10 years.