Prodi is not going to come back. He's not a sleazebag opportunist like Berlusconi.
Will Veltroni take his place next election, or will it be someone else?
With no offense intended, I guess you should really read up on Italian politics. Prodi has no "place", and he did not even run in the 2008 election. Veltroni resigned shortly after a massive defeat in Sardinia earlier this year, and a bland uninspiring ex-DC guy took over before losing to a former Socialist supported by Prodi and keen on a Olive Tree setup.
The PD remains weak, without direction and without real leadership. It has underlying and significant internal divisions in addition to that, and can hardly compete with Berlusconi's well-oiled corruption machine. Even if Berlusconi's ratings are slipping, slowly but surely.