We can bring back Pjaca and still keep Mandzukic. And it would make a lot of sense if you thought about it for a second
Mandzukic to fight for the CF spot with Higuain; Pipita needs to be more rotated by Allegri. Many asking for him to be sold but I think he's been actually very good here and I hope Allegri will allow him to rest a bit more than last season, so he's more fresh - when tired he's less effective. So having both Mandzukic and Higuain competing for the CF spot is probably the best thing we could do, because we don't spend a penny and we've got two very good forwards with different characteristics.
Pjaca to take Mandzukic's spot as a winger. Nothing more to add here.
The rest of the money invest into midfield. Our attack is awesome as it is, midfield screams mediocrity for a couple of years now. We have no starters nor bench players as things stand. I mean, there is Pjanic and Bentancur who in my books are very good but other than that - we need improvements. I'd keep Marchisio and Matuidi is unlikely to leave I guess but that's still a couple of pieces missing. In a perfect scenario we get Can + SMS/Pogba/Kovacic + Pellegrini/Barella. Khedira is probably going and Sturaro should be sold.
The problem with that is if you bring in Pjaca and keep Manduzkic our attack is as follows
Cfs : Higuain, Dybala, Mandzukic
Lw : Mandzukic, Pjaca, Berna, Costa
Rw : Costa , Dybala, Cuadrado, Berna
That would be 7 players for either 3/4 spots depending on whether we play a 4-4-2/4-3-3/4-2-3-1.
I Don't see Pjaca playing at all if that is our attacking options. Also given how this season has progressed, we saw how many times Mandzukic started, and I do not think he'd want to be a rotational player given he still has alot of fight in him.
I do however agree with the midfield, however I Don't see this huge revolution. I expect us to keep the entire midfield that we ahve intact bar Sturaro ( I see him going back to Genoa). I also do not expect Khedira to leave given he still has a year(?, I believe) on his contract. Maituidi and Marchisio will.both stay, and again I believe our midfield will probably be as follows :
Maituidi - Pjanic - Can/Khedira.
I'm not hopeful that the team will change that much, but I'm hoping for the best