well i think Sanam Bhutto should come forward to lead PPP as she is the only child of Zulfiqar Ali Bhutto who is alive now and secondly her personality is not controversial among masses as she remained far away from politics but now she has to take control of PPP for the sake of party's survival .
second option is Bilawal Zardari but his chances are very less as he is Zardari not with a surname of Bhutto !

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" Woods are lovely dark and deep But i have promises to keep And miles to go before i sleep "