Personally I always enjoyed playing the Ming in previous versions when I felt like smashing the hell out of Asia for a few minutes without turning on cheats. I tried playing with the new faction system and didn't like how I had to keep micro-managing domestic sliders and praying for leader stats.
But finding some way to nerf Ming is essential to preserve the gameplay, because without it you find Ming making it to Germany before 1500. My new favorite way to play in China is to take Manchu-> Qing. Conquering all those delicious Chihan provinces feels so much more satisfying than starting with them all.
I think another way to keep Ming chained would be to re-think the culture, religion, and political situation of East-Asia. Even after centuries of state-supported homogenization, the ethnolinguistic map of China looks like a fruit salad, and Southern China really only shared similarities with the North on paper (literally, the writing system was the same) until modern times. At the very least, Japan, Korea, and the Manchu could be in separate culture groups. And all of China is a single religion, "Confucianism"? And the Manchu are practicing it at game start? It just seems all-too convenient. Now I love the changes in Divine Wind, but I thought we'd get a little more depth than we actually did.
I am also not sure why I see Kyoto becoming Hindu, but oh well.
I would like options for Ming to ditch the Celestial Empire and/or factions, maybe something triggering with losing the mandate of Heaven or a change of religion, that could have the empire devolve into lesser states or form a republic or something else ahistorical but somewhat plausible? Japan can ditch the Shogunate, but the Chinese can't? I think with enough buddhists and wokou raids, you could get the peasantry riled up enough to throw out the Mandarins (or at least replace them with different Mandarins).