I haven't read every post in this thread so forgive me if it's been mentioned.
Gut says Greyhawk and I'm hoping it's right. Vecna is a high visibility name at the moment and will be for the next year or so due to the popularity of Stranger Things. If we don't get a straight up Greyhawk "revisit" I wouldn't be surprised to see a remix of the Vecna trilogy being a location/planes jumping adventure. I wouldn't be mad about either.
