Even though Filoni explicitly stated that it was an actual death and he wouldn't be coming back. One reason why I believe this is because he's served his purpose. He represents Kanan's fear in Season 1, fear of failing his friends, and when he says "Now I know that there's something stronger than fear... the Force." He destroys the Inquisitor's Lightsaber which, as The Visual Guide said, he used to strike fear into his enemies. It was a not-so-subtle symbol of fear itself for both Kanan and Ezra, and Kanan has overcome it.
The Inquisitor lost his main asset, and he knew what failure meant for him, so he gave into his own fear and took the coward's way out. That was the main focus of this season. Now they're moving on to other focuses, a larger spectrum in the story.
But, nonetheless, some of the writers will probably want to pander to viewers' theories and bring him back all Admiral Trench style, and you lot will hand me a big "I TOLD YOU SO!" But in the mean time, that's my theory and I'm sticking t it.