I think CONSIDERING retiring the N° 10 shirt is enough of a recognition.
Actually withdrawing it would stain Del Piero's legend (it would be yet another polemic). There will be many other 10's @ Juve but none will ever wear it the way Del Piero did. Therefore, no need to withdraw it to highlight what facts & memories already do...Plus, it's not in Juventus' philosophy to do this, get over it, not in a million years. We will have other greats in our squad. We're not Napoli, nor are we Livorno. Del Piero shines all the more, as competition is stellar: Platini, Baggio...Need I say more?
I'll add that Maradona's case is VERY special. To me, he's the greatest football player ever, maybe ronaldinho will reach this status soon. Maradona was a pure number 10. Ronaldinho is the only player able to fill his shoes. Zidane & co simply cannot.