Holly can also try to flirt with Ian later on in the story, if they don't get together initially. I can't recall if it's only with a high change variable, but my assumption is that they might have a sexual scene or two at some point, perhaps leading to a more casual relationship between them, depending on her relationship with Lena and such.
I also think it's entirely possible she could have one of those "single and proud" kinda endings where, if she doesn't end up with either main but has high change variable, she becomes content with her newfound sexual expression without having to end up with anyone.
As for all the Stalkfap stuff I just see it as a natural progression given how we can already have Lena takes photos of her and she can allow Mark to photo her slobbering all over his cock. Perhaps she won't post anything herself, but I think it's entirely likely that either she or perhaps Lena becomes reckless with it. Eva professes to want ORS to be more grounded than GGGB, but crushing that little writer reputation under a deluge of sexual content from Lena just seems too juicy to not happen, haha.