I ve seen two main scenarios of "what if" Billy alive in the s4, and it made me want to come up with my own take on it.
I like the idea that in the Upside Down he wouldn't be stuck alone, but with Hopper. First - it keeps the plot more cohesive and gets rid of that ridiculous Russian storyline. Second - it has good potential for their dynamic, like a mentor/mentee (father/son tbh) thing, which would give both of them a lot to think about.
The Hawkins idea I like a little less, because it pretty much breaks the entire structure of season 4 and takes away powerful moments like Max's letter, and I'm rlly like her arc in this season. But a depressed Billy trying to get his act together and tagging along with the kids? That would be interesting to watch.
P.S. yeah, in both versions he's a little bit messy. In the Upside Down because there's no shower, in Hawkins because he's depressed."
