You know what? The only way I could see this happening is because Slutan is guy with a lot of pride and Juve is his ex that gave him the least love, so he may want to win her heart to satisfy his ego, then leave.
He's very individual, we maybe can't sign a better forward than him, but we can definetly build a better attack without him, case in point Mourinho's Inter, their attack was way more stronger when they got rid of Ibrahimovič dependency and signed Eto'o, Milito and Pandev, who are all arguably lesser players than Zlatan individually, but together were way more dynamic and tricky. Ibra proved in Barca that he's very limited if he's not the absolute focal point of everything in the final third.
Apart from us and maybe Bayern, I don't see many big (with CL winning potential) teams signing him if he decides to leave PSG.
Depends on the circumstances, Eto'O can't win the scudetto alone, Zlatan can. With Zlatan you better forget about CL, Eto'O is an absolute beast in the knock-outs, cold as ice in the deciding moments.