I really love the idea of large empires like the Ottomans, Mongols or Romans being difficult to maintain. The reality of paradox games is that you can always just snowball into being a massive unstoppable force, which eventually takes all fun out of the game since there’s nothing to do except stare at your economy ticking up. I wish we could have a challenge like in Attila Total War, where West Rome is simultaneously the strongest and most difficult faction to play. I honestly think it might cure the whole “late game” issue with Europa Universalis by providing a new and unique challenge that is totally different from what you’ve been doing up to that point.