I think most people who wanted to purchase this plugin already did it and perhaps there’s not new interest as the plugin is clearly abandoned for a while (not entirely, but mostly).
New potential customers for s2member just move on to other solutions when searching for a membership plugin because they visit the forum and they see it’s outdated.
I think that we can somehow try to bring it back to life. It might require a lot of work, patience, time and perhaps even resources. The code is open, so anybody with enough knowledge could have come in and helped, but this never happened either. I don’t know any php, sadly, or I’d have done it a long time ago, at least on minor issues like s2member’s terrible (lack of) routines around failed payments, demotions and reupgrades upon late payments, for example.
@openmtbmap mentions issues surrounding stripe’s variables that’s another item that needs to be fixed that sounds a bit easier for someone with php knowledge, as I assume it would only require some code modifications to use the fields we can see (sub and customer fields) instead of using the hidden array. Or, at least, show the hidden array on the user profile, even if on a raw format, so we can easily edit it when necessary.