That is, IF the show gets picked up for a 31st season by FOX, which hasn't officially happened, yet.
Turns out, at least according to producer Al Jean, 2019's Treehouse of Horror XXX would be episode number 666, something he says they've been planning since 1989.
"Next year, Treehouse of Horror XXX will coincidentally be Simpsons episode 666," Jean told[...]
