Was looking at SK novels/paperback...last night I think it was...saw this on a white page: it was a pleasure to burn. --Ray Bradbury, Fahrenheit 451 Forget now what story that is...what's the word? an epigraph? too? That was my sense, that there would be a cleansing.
'salem's Lot is mentioned in a few of the later books, even that it was swept by fire (if I'm remembering right), but it's still a creepy place that people tend to avoid. I took from those things that vamps continued to live there after the fire.
Yes, there was a cleansing, but it didn't work out so well. The Lot was referenced in many other stories. Read "One for the Road" from the Night Shift collection for a post-novel story from the Lot. Without giving any spoilers. The Lot was still active during Pet Sematary, and was referenced as a "Company Town" for the True Knot in Doctor Sleep. Callahan also fills in the story a little during one of the final DT books (can't recall which one right now, but he describes going todash to visit Mark) . . . probably Song of Susannah, but I'm not 100% certain.