These are my top want themes for PINS, of which I think have a great chance of happening:
TRON (VE / Revamped version or might make an '82 version etc)
Would it make sense to strike while the iron is hot & release Stranger Things now with having 1- (likely) 2 more seasons left, or do they want to wait to see what other content they could add to the machine. I think at this point with the end of Season 3 they have PLENTY to incorporate. Jaws will celebrate it's 45th anniversary next year, Jurassic World just got a re-theme from previously Jurassic Park in Hollywood Universal Studios, with Orlando Universal Studios about to receive a Jurassic World Roller coaster in 2020/21. Also in 2021 the final installment of Jurassic World "3" comes out. Disney's currently building the Tron rollercoaster and celebrating their 50th in 2021. LOTS of great titles or at least themes to me on the horizon.
Stern's popular previous TV Themes made into pinball;
I can't see them or [insert any pinball company] not wanting to pump out a Stranger Things Pin as IMO the license is insanely HOT right now. I'm actually surprised Big Bang Theory never got made. I'm sure of it that at some point between 2019-2021 STRANGER THINGS "WILL" HAPPEN.