Just my 2 cents, but PLEASE NOT YET ANOTHER FEUDAL JAPAN. I'm not hating on Japan, but we already have tons:
- Rokugan
- Oath of the Dragon Samurai
- Kamon
- Mists of Akuma
Heck even Kara-Tur itself focused almost exclusively on the Kozakura and Wa. Not in the original boxed set, but nearly all of the modules were set there (except for the best Oriental Adventures module: Mad Monkey vs Dragon Claw).
But the Kara-Tur setting had so much more going for it. Shou Lung, Tu Lung, Koryo... I want the full spectrum of fantasy feudal Asia, not just feudal Japan. And while we have a lot of 5E campaign settings within a fantasy-feudal-Japan analogue, we surprising have almost none for the rest of Asia. Just 'Undying Corruption' (which I don't own but looks pretty great) which is a fantasy-feudal Korea setting (good idea since Korea has been banging out some great fantasy shows/movies lately). And nothing at all based off of a fantasy-feudal China (Imagine how cool it could be to have a Warring States period wherein 'great generals' rampaged back and forth similar to the 'Kingdom' manga/anime).
So I'm hoping that if Kara-Tur 5E does happen, it will at least resemble the original boxed set from 2E, with a broad focus on all of Asia and not just Japan.
And I want lots of martial arts. Cultivation. A place where the Murim heroes run wild. And lots of Asian monsters.
By the way, if they do decide to do Kara-Tur 5E, then they should just immediately hire the guy who wrote 'The Relentless Heavens' and transport that supplement to be used in Kara-Tur (I know someone already mentioned it). It's one of the best 5E supplements I've ever seen, and it contains a new levelling system that can be easily bolted on to the existing 5E framework for martial arts cultivators, so that any character (if they can find a teacher, or a cultivation method) can decide to level up traditionally, or level up cultivation, or both. It's fantastic.
I know it's too much to hope that the mindlessly cowardly PC morons will ever use the 'Oriental Adventures' moniker again, but if Kara-Tur 5E happens, it damn well better be still called 'Kara-Tur'.