The writing in the first episode of S5 is pretty rough, just from a dialogue standpoint. Everything is forced, and obvious, and they are making it clear from minute one what everyone's conflict is, at the expense of any subtly. I'm thinking specifically about the scene between the boys in the hallway after Dustin gets threatened the first time, even the amazing chemistry of the four of them could not save how awkward that writing was...good lord. Anyway, this is why it seems clear (to me) that they aren't setting up a Mileven breakup, and they're probably not setting up Byler endgame. Because if they were, it would have been way more obvious, the way that they set up the whole Steve-Nancy-Johnathan love triangle from literally the minute go. I know part of being a Byler fan is picking up on these tiny little details, like the One Way sign in Mike's room or the music playing underneath every scene, but the thing is...the show isn't that subtle in most cases. Every other romantic relationship was made pretty obvious from the minute the two characters had a scene alone together, Hopper and Joyce, Nancy and Johnathan, Lucas and Max, etc. Even though they don't kiss when meeting up, which I find to be kind of interesting, that Mileven scene on the roof seems to be just a reestablishment of the relationship, like the Joyce/Hopper scene right before it, assurance that they're happy together again after last season. We saw it in the trailer and wanted the sunset in the back to mean "the sun is setting on their love" but tbh, they probably just did that because sunsets are pretty, and they're romantic. The show might not be as subtle as we want it to be, much as I hate to say it.
I'm not saying at all that there haven't been major hints and details in the show that point toward reciprocated Byler, there definitely have and I'd still consider most of Season 4 pretty queer-baity if they end up doing nothing with it. And I'm open to other arguments! But yeah I'm having my doubts. Honestly, I do love the ship and I'll be sad to see it not manifest, but I'm more upset at the idea of all the fans who were homophobic and cruel getting to say "HA HA we were right to be shitty to all of you because you were actually DELUSIONAL and not everything is GAY you dummies" like guys...it's a TV show. Let people write gay fanfiction I promise it doesn't hurt anyone, and you don't get a pass to be an asshole just because you ended up being right. Lets all be nice to each other, okay?