^Phil. politics is a circus. Even I don't know who I'll vote for President next year.
For me, Duterte's age isn't really a deterrent, as long as he keeps himself healthy. Look at FV Ramos, he's 87 and he's still alive & kicking. But then Ramos was a military man and maintained his exercises even while President.
Erap was different - he was a known gambler and drinker and was known to gamble into the early hours of the morning, and that's when he approved shady deals (or so it was said).
As for Duterte, I don't know if he'll be able to handle whole country and I'm also queasy about dictator-style assassinations.
I wouldn't trust the mayor in my hometown with the whole country. I would vote for him again if he ran for mayor as he keeps my town clean & orderly. However, he has said that it's his last term since he's also getting on in age and probably wants to retire.