I really hope not. The dark ages need their own game, the Frankish feudal model from the high Middle Ages they use wouldn't work well with the migration era, at any rate. Even the English melting pot can be wonky. From my experience as a modder, melting pots are notoriously frustrating to deal with, not so much in the difficulty of coding them (Kyou only really need a little experience to pull one off, or just copypasta the English one), but because they can be very unpredictable. For instance, in the old version of the CKII+ mod there was a Crusader/Outremer/Levantine melting pot, but it was really wonky and sometimes you'd see the cultur in random parts of Europe. In one of the streams they mentioned there wouldn't be any great shiscm - they'd considered it but decided it wasn't worth the effort.