I think this is what HumanKind is trying to trying to achieve. Only without the preconceived notions that you've built in (Mongols -> Timurids, Hellenes -> Minoans). Essentially, you're saying that predecessor empires could only have evolved as they did historically, into one of their actual offshoot empires, and player choice should be limited by what happened in the real world. HK appears to be taking a broader mindset, and allowing for evolutions that didn't historically happen. I'm not saying what they're shooting for will work as a game, and I'm certainly not saying that everyone will like it. But it is ambitious. And if it encourages Civ 7 to take a different look at the "static culture" mechanic Civ has utilized to date, whether in a form that you've articulated or otherwise, then that may well be a win-win.