pirlo was/is not a symbol of milan as daniele is to roma
pirlo has been at several clubs but he stayed longer at milan. rossi is born and bred in roma. it's like trying to get the ryan giggs off of man u. not possible.
If you go by being born into the club, then of course it's not the same. But I think Pirlo spent enough years at Milan to be called legend there, until he fell out with management.
As for DDR, I think it depends on how Roma's season goes. If they continue to do well, I doubt he'd leave to anywhere. But if they end up falling apart again I wouldn't be surprised if he left this time, I just have a feeling his loyalty might not go quite as far as Totti's. Probably more to somewhere like City or PSG than to Juve or any other Italian club though.