Let's say both Japan and Korea kick into high gear around the same time—what happens?
A fight over China?
They go their separate ways? Korea goes into China, Japan goes off to the Pacific?
What happens with Russia?
Is the Japanese treatment of the Taiwanese (i.e. great) their future standard as they gather some sort of colonial empire in the Pacific/parts of China or do they shift as in OTL to their treatment of Koreans (i.e. very nasty)?
Likewise, if the Koreans bite off a big chunk of China how will they treat their new subjects?
As long as we're adding a Meiji type Korea, what about Thailand? They were closest to pulling it together after Japan—what if they to pull a Meiji? (Their problem was being stuck with both the French and the British, playing them off against each other, and gradually trading territory for independence.)
What does having two or three advanced Asian nations do to the rest of the world?
(I leave out China because an early modernized China presents a fairly obvious answer, plus it gets discussed a lot anyway.)
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This thread was sort of related)