The closest thing I've found to what I was hoping for was Roleplaygateway https://www.roleplaygateway.com/roleplay/the-multiverse
You can create a game with a built in 'hub' chatroom like a OOC room, there are tabs for the characters and the information written for them; tabs for locations, I've even seen a grid with a graphical interface on some games, and you can make private rooms for scenes, the logs of which can be kept up and sorted by story arc.
The only problems are A) The scene rooms appear to be forum-play style exclusively, when I'd like the ability to do both when schedules don't quite match up; and B) It is ACTUALLY impossible to search for any specific type of game in its own system. There's a heaving mass of one-off games, and the search function literally doesn't work, and doesn't even pretend to offer the functionality to sort by genre, or give a dropdown list of tags to add or anything that might help sort through it; and, the eternal problem: how the heck do people find this? I mean, I did, but I had to strangle google to make it show me something other than Dragon Age.
Also it doesn't seem to have been updated by the people in charge for years. So, like MUing, it's kinda something you have to either already know about, or stumble onto/get invited to.
Something like this with more functionaity, more of a visual/graphic interface for things like bulletin boards and mail, but keeping the old style of live RP and ongoing stories, while allowing people to chuck poses in forum-style when they can't meet up live, would be pretty great imo.