I'm of the opinion that experiments will end up being done on his body in an attempt to bring him back to life, OR he isn't actually dead yet but without said experiments pretty much will die. It will be condoned by Varis though more...unsavory ones even by the usual Empire villiany type standard will be done without his knowledge. Success will be had but Regula certainly won't be quite as sane afterwords.

This will bring him closer to being a Kefka expy, though I believe that will be the extent of it. Any further actions that paint him as such will end up being subversions of expectations.