that's only a small part of the problem. China especially lately has a problem with if you print anything they consider belittling them or idolizing their rivals they will keep your book out of their country. Even if you try to disguise it. I don't know how much Hasbro is worried about the China Market but it is something to consider
Is it possible to have a class called a ninja and not be already "culturally appropriating"? If you added to that class the attributes of being stealthy and using strange farm implement based weapons does THAT make it "culturally appropriating"? How about if you make that class native to a far away land not the center focus of the campaign?
The question I have to ask is: Why have a ninja class when the rogue currently fills that archetype or the monk subclass that's already called a ninja in its description in the PHB? There's nothing Asian archetype that I'm aware of that would remotely require a new class. You could maybe add some subclasses, but present them like the samurai subclass in Xanathar's--the only Asian coding is the name.
TouchèNow I am awaiting the moment when somebody says Italians can't produce spaguetti Western movies because they aren't Northamericans.![]()
* Now I am awaiting the moment when somebody says Italians can't produce spaguetti Western movies because they aren't Northamericans.![]()
I very much doubt it. Kamigawa block performed very poorly and the higher-ups would much rather sweep it under the rug and make a new setting to fill the same niche than revive it.WOTC keeps adding MAGIC the Gathering settings to D&D, so the next Oriental Adventure will be for sure Kamigawa, then people on DMGuild will use the rules and subclasses in Kamigawa to build stuff for Kara-Tur as well.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.