What might happen in a sequel to Poe's "The Tell-Tale Heart"?

Well, that's a fun question! I would expect that the narrator would be in prison, trying to convince his cellmate of the evil of the old man. He would again try to justify his actions. He would not be in the least remorseful.

If I were the cellmate, I'd be careful not to look him in the eye, take the bottom bunk, and sleep with a shank under my pillow. If the narrator claimed to be bothered by the beating of my heart or anybody else's, I'd bang my tin cup on the bars as loudly as possible until the guards couldn't take it anymore and put me in solitary...