The ever-growing Stranger Things 4.
This kind of trans-media transition already has some precedent. Two novels were released before Stranger Things season 3 hit the streaming service in July 2019, and they highlighted two characters who had key climaxes in the made their roles in Stranger Things season 3 even better – proving that a type of multimedia strategy is already in play.
How, exactly, would this work in Stranger Things season 4? The TV series itself already has a growing accumulation of storylines that will need some type of resolution or revisiting before the show comes to an end, whether that be after four years or five – Dr. Martin Brenner and Jim Hopper both still being alive, Eleven’s powers being lost, the Expanded Universe would just be another arrow in the narrative quiver, and Kali Prasad would prove to be the natural link; with numbers Three and Nine-Point-Five already safely escaped from Brennan’s Project Indigo before Stranger Things starts up, they go on the hunt for Eight (and her hangers-on) in Into the Fire, finding her continuing her murder spree three months before season 3 takes place. She, in turn, reveals that Nine, who had been presumed dead for the past seven years, is still alive, and the three ex-Hawkins “siblings” set out to save her.
That Kali has made with Ricky and Marcy – and just might with Jamie as well – is hugely important, as they could be assimilated into her Chicago posse, and thus arrive on TV screens when Eleven, Mike Wheeler, and the rest of the Hawkins group finally catches up with them all. Now that the Soviet Union has been revealed to be another major player in the plot to potentially weaponize the Upside Down and its various lethal inhabitants – and now that there’s the potential that Eleven’s powers back in the process.
Assembling such a team for such a daunting task would fit in with the franchise's mythology, to boot; not only have the various episodes, novels, and comic books centered around such a storyline already (Mike and his friends finding Will in the show, X-Men vibe that just may be settling upon Stranger Things 4.
And just a development would also, in turn, pave the way for the final piece of the Stranger Things backstory: just who was test subject One? In this way, the Expanded Universe could continue to flourish even after the Netflix series finishes up its popular run.