I think your proposal is fairly grounded, but I know that it is often easy to get carried away with elaborate proposals to make or redesign civilizations. With that said, I think if the devs implemented a Revolution design in the manner which you suggest, people would expect a similar feature for all other civilizations. Should Britain get the ability to dissolve the Union into Ireland or Scotland, for example? Should Spain break into Castille and Aragon, or perhaps for the later period of the game, Bourbons vs. Habsburgs (War of Spanish Succession), or Bourbons vs. Bonapartists (Napoleonic Wars)?
Though, now that I think about it, giving France the ability to “revolt” into either Bourbons, Bonapartists, or Republicans would be interesting. Perhaps the developers will settle for having the flags change with each age-up.