My prediction is that El will die based on the fact she was originally intended to die at the end of the first season, but I don't want her to... I'm worried the Duffers will go down that route and have her needing to sacrifice herself to close the Upside Down.
I feel that Joyce has been increasingly sidelined so the show can spend more time on male characters' man-pain (e.g. Hopper's tragic backstory, Steve's continued obsession with Nancy) which I hate, so I'd like this turned around in season five but I'm not optimistic
I was not aware El was supposed to die in season 1. I've definitely thought about her possible death in season 5 being the ultimate sacrifice that's needed to destroy the UD, but I can't see them killing El off I really can't. I really am riding the "No one is going to die" train very hard lol
I don't know if I'd totally say Joyce has been sidelined, but also when you have so many characters in a show it's impossible to give equal amounts of screen time. That's like a big flaw in the writing by adding so many characters, but also I can't imagine the show without all the characters either! It's complicated.
Also, they had three/four separate storylines in season 4, and she was a major part of the Russian plot line I think! But I definitely see why you could view it differently too!