AHC: No nationalism

[Tripwire]

Something has to replace it as an identifier. I suppose the next best idea is the one that nationalism replaced - the 'dynasty-state', where identity was more along the lines of who you recognized as sovereign. So you'd have 'Habsburg' subjects and 'Romanov' subjects and so on.

To piggy-back on this, I agree that something has to replace it as an identifier, and I think an even better replacement would be religious identity. Make religious sect really, really important, and keep it that way, and the populace's identity will solidify around shared religion and not shared cultural/linguistic ethnicity.

 

[Fabius Maximus]

by which logic, a more successful EU fits the bill
less admission of backwards countries, less divisive debt problems

FWIW people in the UK at least don't generally take European elections as seriously as they take general elections. So, I could totally see a situation where people in a very decentralised polity don't really care that much about who's in charge of the country as a whole.

I don`t know much about Japanese history, but focussing on Europe, I think there are two periods of time in which points of departure are promising:
a) either have Antiquity end with an intact and strong Roman Empire
b) or have the Middle Ages end with no large linguistically homogeneous monarchies of the England/France/Denmark/Sweden/Portugal type around.
Since a) has been elaborated on by many people, I`ll just say a few words about b).
I see two possibilities to bring b) about.
1) Either the counts, barons, magnates and other knights manage to modernise and shape early capitalism themselves, keeping the checkered medieval landscape of tiny polities around throughout the industrial era, possibly later being overthrown by a revolution of industrial workers.
2) Or the commoners (craftsmen in the towns and peasants in rural parts) manage to establish early stable confederacies of local polities like the Swiss Confederacy.
Perhaps a combination of a more flexible Hanseatic League, stronger Italian sea republics, and keeping the divisions between France and Burgundy as well as between Aragon, Castille, Navarre, Portugal etc. around for a longer time until they`re all overthrown by revolutions...

A surviving feudal system would be interesting, although I'm not sure how plausible it would be if the IR goes anything like IOTL. Then again, I suppose the town burghers did have a place in the feudal hierarchy, so it might not be impossible. Maybe a situation whereby the towns/communes are the basic political unit, and these then swear loyalty to a higher monarch?

(Come to think of it, that was theoretically how the Roman Empire was set up: a load of separate city-states which had all agreed to recognise the Roman People as their overlords.)

I wouldn't say that Switzerland had no trouble staying together. The Sonderbund war for example was not only about liberalism vs conservatism and a conflict between the confessions, but also about the divide between the French and Germans.

Well, "no trouble" might be a bit of an exaggeration, but compared to, say, the Balkans, Switzerland looks like a beacon of stability and inter-ethnic harmony.