Well Renall I don't think that's bad but it's also a speculation on it's own. Not that this is a bad thing at all.
Rokkenjima Prime is a speculation on it's own.
Personally I think ever since arc 1 they've been giving us too many hints that Rokkenjima is fictional. It's not on any maps. No maps of it existed. Krauss couldn't find Kuwadoria
n by touring the island on helicopter or something. Kuwadorian is anyway very hard to swallow the existence of. More then all of that tho, I always found it very disturbing that while half the characters either lives or spends most of their lives on Rokkenjima, some (like Jessica) since birth, Beatrice in her first letters always says "People of the Ushiromiya Family, welcome to Rokkenjima". Then you ever have Battler going in depth in episode 1 about what the Ushiromiya family would be if Kinzo didn't find 10 tons of gold, that lastest part added with what arc 8 tells us about Kinzo... seems to again hint a Prime without a Rokkenjima (or possibly any murders).
Personally this is what I think. A lot of things exists only within the story, the Shkanon thing, Rokkenjima, 10 tons of gold, etc... Most things that "might make some level of sense, but honestly, you'd only ever see that in a story" - all these elements I believe only exists within the Yasu stories. Rokkenjima is the "setting for a mystery murder story" that Yasu was writing and nothing else.
And Ange's world should be obvious by now with even herself calling herself a piece, that it is yet another fiction. It's the fiction in which all of this is real.