If the Philippine economy improves, Duterte's popularity will only grow. He rode in as a sort-of agrarian populist socialist (not in the progressive sense, mind you) fighting for Philippine sovereignty and supposedly against neoliberal policies. We'll have to wait and see if his reforms actually end up working or not.
But frankly, take away his drug-killing stance and he basically looks like any other somewhat left-of-center politican.
Yeah..take away the warmongering and mass murder...and Hitler was a veritable Frank Roosevelt.
Sometimes you can't take these things away.