IMO I see Prandelli as the next Marcello Lippi. He spent years in the 90's managing the youth team of Atalanta which produced a lot of talented players including Tacchinardi and Montero. Later, He did a really good job at Parma. At Fiorentina, he has done a GREAT job taking the team from mid-table to the CL qualifiers 3 years in a row (excluding what happened in calciopoli). I think now is the right time for Prandelli to manage a big team like Juve.
Gasperini is a very good option too.
It seems whoever 'Fails' to qualify for the CL will leave his team and join Juventus. I Hope they don't both succeed