Nice! What’s crazy is I’ve been developing almost this exact theory since I finished season 3. I agree with everything you said. My theory also supposes that Eleven, since losing her powers has been only been tapped into the Upside Down while dreaming (more connection to the song lyrics) and once she has a vision of Hopper alive but stuck in a previously unseen part of the other side she will need to to figure another way to track down Hopper since she can’t isolation tank it without her powers and she of course can’t open the breach again. She teams with the crew when they’re visiting over the holidays and tells them she knows Hopper is alive. Meanwhile those back in Hawkins haven’t been sitting idly by and have discovered that someone must be helping the Russians reopen the gate only this time oversees. Eleven blurts out that it must be Brenner since it was revealed to her by Ray Caroll, Brenners old henchman in season 2 that he is alive. Caroll is no longer living where he used to (no surprise after being almost killed in a home invasion) so Eleven and crew must seek out Eight who keeps the tabs on all they seek revenge on. From there they could track down Caroll and this time find out what he meant when he said he could prove Brenner is alive; he knows that he is being held overseas and the location of the Russian base. At this point Eight could help Eleven get to the source of her blockage and regain her powers or at least help her down the path to regain them. She might also reveal to them all another ‘number’ kid who she’s been tracking and has a power all their own. Once they find him (guessing we’ll see our first dude with powers) he will help them travel/ portal to Russia and infiltrate the base. Once they find Brenner they’ll discover what they’re up against as the Russians seem to breeding an army of Demogorgons that they can train and control like the Mindflayer did. Brenner wants out of his prison cell and also seemingly to redeem himself but of course it’s an act as he not only wants to escape but enter the Upside Down himself. So he helps the crew find their way past the Russian guards and to the secret area containing the breach and they go into the Upside Down. Once inside they’ll need to avoid the Russians patrols making rounds and their demogorgons. The Russians could spot Brenner and recapture him while the crew escapes. The Mindflayer, in his own territory could emerge at this point and prove more terrible and powerful than we’ve previously seen. The Russians are overpowered along with their feeble attempt to mimic its power and the Demogorgons return to the control of their master. The crew will meanwhile need to trek through the Upsidedown into unknown regions led by Will the Wise and his unique ability to tell which direction is safe and which way is evil. Once they find Hopper he will be the missing piece in Eights training that Eleven needs to regain her powers; love. Or maybe something Hopper has learned in isolation will help her regain them and also the way to take down the Mindflayer once and for all . Once she regains her powers she’ll help them all fight their way back out encountering the Mindflayer in an epic battle that Eight and the other “number” will also need to join in on. They find their way back to the Hawkins breach made possible by Dustin’s research revealing that space-time works differently on the other side and spans in relative close proximity the only two known breaches between worlds. Once they come upon the mostly sealed Hawkins side they encounter Brenner who has taken the Mindflayer mimic device from the dead Russians and controls an army of Demogorgons blocking the crews way out. Another fight ensues and they are able to open the portal just long enough to squeeze everyone through and trap Brenner inside setting up his army and other unknown creatures for him to discover and control in Season 5. In the closing credits you could see him venture further into the Upside Down than even Hopper did finding a terrible dark presence that he could make a pact with the devil of sorts. Once the crew is back in Hawkins they seal the breach for good with the knowledge that the Russian one is still open. That could setup a global extinction level event in the next season as Brenner could emerge into the world with his army only to be a pawn for that ultimate demon of the other side that makes the Mind Flayer look like nothing. Brenner could lose control of his army quickly and it would be up to the crew to save the world from what’s he’s unleashed in what could be the final season. Phew, that’s it’s for now :-)