God will mercilessly torture the scumbag for all eternity, unless he repents. There will never come a time that God thinks he’s been tortured enough. He’ll get his. In spades.
While I don't wish Hell on anyone, he will do it to himself. Just as people do not know and understand how beautiful Heaven is, I also believe they have no idea how horrible Hell will be. My guess is, that it is a million times worse than the worst thing anyone can imagine in a million lifetimes. You are right, merciless and unending. If people were just made aware of this, one would hope the fear alone should move them toward the Lord.