The MOM website says one has to apply for an EP if one wishes to continue working in Singapore after the PEP has expired, as it's not renewable. Whether they actually approve the EP after PEP is yet to be seen as the PEP was introduced in 2007 and the initial PEPs (mine included) will expire only in 2012.
Here is my guess.
The PEP holders may receive an 'invitation to apply for PR (perhaps with in principal approval)' letter from MOM/ICA 3 months in advance before the expiry of PEP. The PEP holder will have only 2 options then. One is to accept the invitation and become a PR or ignore the letter and apply for an EP.
Of course, many of us, PEP holders wish/hope that it can be renewed.
Let's wait and see what the future holds for us.

It's in my blood. B(e) Positive.