The odds are very heavily stacked against him. He's a hick, basically and Manila/NCR/Luzon machine politics dominates this country.
Only 3 of the 15 presidents of the 15 presidents of the Philippines, have been born on islands other than Luzon, and none of them, for over 50 years.
However the field of opponents Duterte faces, all of whom are Tagalogs, seem quite weak.
Despite that, I think one of them will prevail and Duterte will do well, to come second.