Juventus plan to strengthen their squad in the summer by raiding their big rivals in Milan.
Juve president Andrea Agnelli rates Santon highly and tried to sign him in January. But Inter's demand of Claudio Marchisio in exchange scuppered the deal.
A swap could still happen if Agnelli is willing to part with Momo Sissoko or Felipe Melo.
In Pirlo's case, the midfielder will make a decision on his future closer to June.