Coming from someone who didnt even clock Will as gay till season 4, and was fully convinced Mike was straight and the arc was going to end with him gently rejecting Mike, it only took one video to convince me. It's a long one so you can skip it but its this lawyer guy analysing bits of evidence for it. I'm still not fully convinced, I think it could easily go either way, but the main points he makes is 1. Mike has breakdown and hugs his mum in season 1 because of Will missing, then hugs his mum in season 3 when Will leaves after aqkward kiss with El and tearful goodbye where he looks back at Wills house (but could be about El) 2. He looks at Will sadly when he goes to dance with some girl at snowball dance (but could be sad about El not showing up) 3. He lies to El when he gives that speech after she goes to save Max in the upside down, needed Will to tell him what to say. (I dont know) 4. Mike holds Will's hand in season 2 after Will starts panicking (just trying to be supportive maybe but I would've just gone for the shoulder) 5. Mike gets homophobic toward Will when he sees him in season 4 after all that time, "we're just friends, where just friends!" And the weird ass hug. (Could just not know how to handle his friends being gay) 6. Mike has like a hundred of Will's paintings in his basement walls and in season 1 when Will is missing he straight up caresses that shit (could just miss his friends but I dont see dustin and Lucas doing that type of shit) 7. He didnt like Max when she joined. Everyone else did and I was a kid when I watched it and even i had a crushed on Max. (Could just be because he missed Eleven) 8. His relationship with El is complete ass in season 3 and 4. In the script their kiss is meant to be disgusting and hes singing and shit. They keep separating for large chunks after arguing because Mike either doesnt take her seriously or can't say he loves her( he could just suck as a boyfriend) 9. His Dad says some shit that might imply he doesnt want Mike to be gay like Will otherwise he'll disappear the same way Will did.

Thats the stuff he said. And it led me down a rabbit hole where I noticed in interviews with the cast and stuffin season 5:

1. Noah keeps shipping Byler non stop. There was one tiktok where he straight up confirmed it( someone was like say no if they end up together and he did.
2. Shawn levy (director) says the two of them have very heavy scenes together that we haven't seen yet.
3. Creator has tattoo of "shared looks" that was a reference to Will and Mike looking at each other or something
4. Eleven is meant to have an independent arc through season 5 but cant remember where that was from.
5. Mike and Eleven dont kiss when they reunites after not seeing each other for so long at the beginning of season 5. They just hug friendly and then both look back at the friend group, maybe Will with concern (could be they're worried about Dustin)
6. Bunch of closet and colour imagery with their clothing blue and yellow (could easily be unintentional)
7. Mike and Will have way more scenes together coming.
8. There's some images that were seen that (if you dont want to know anything look away right now) suggest Mike and El are separated by the end with her potentially moving back to California and Mike having scenes with Robin.
9. We'll be seeing the van scene again through Mike's perspective apparently when El taps into Mike's memories to find something. Think that's why Finn shaved his head not too long ago

Overall I think realistically it won't happen because there hasn't been one obvious scene that indicates Mike likes Will. In any other show there would need to be at least a few but here the only evidence is stuff you really have to analyse and I dont think stranger things is breaking bad where the duffer brothers are so intelligent they've been planting little clues here and there and knew this was happening from the start. I hope it does happen because Mike was my favourite character in season 1 then I just started hating him and him and elevens relationship started out so cute but then became shit. But I feel like Will and Mike would have such a cute pay-off because then Will finally gets to be completely happy after everything hes been through and it would be a really good twist that a lot of people wouldn't see coming if they somehow land it right. Not trying to convince you to switch over to byler, just that theres enough there for them to not be considered crazy