Source: Forbes
Promoting boxing was pure genius for ONE, and especially getting the SE Asian World Champion from Thailand on their roster. Even while most people tuned in for the boxing match, other forms of martial arts got enormous exposure, and this is only a boon for ONE.
They're doing things the right way, by becoming a martial arts org and not just an MMA org. The ceiling is high, and they're going to grow in popularity more and more, whether they break into the Western market or not.
Some believe you need exposure in the States to be legitimate, and it simply isn't true (re: PRIDE). The market ONE is growing a lock on dwarfs the American market, and is a market the UFC has been unable to successfully break into (which is why they rarely hold shows there). With ONE ready to bust into the Japanese market, we are going to witness some exciting shit in the near future.
Bellator is taking a similar approach, and is obviously studying ONE's game, by breaking into the European market, and claiming a portion of the world that the UFC doesn't have locked down.
I, for one, hope they both succeed in becoming global competitors to the UFC.