CS6 hasn't been announced yet, but it should be very close. When it's announced, the answer to your question can probably be determined.
You'll find out soon enough: http://www.adobe.com/special/cs6/launch-event-desktop.html
In the mean time, if you haven't already upgraded to CS5.5 now is a good time. You'll get a free upgrade to CS6 when it ships.
Japanes will need a seperate program as in prior versions (though there is the in-tools.com option at http://in-tools.com/products/world-tools-pro/.
However what has not been made clear in all today's announcement, if middle eastern or japanese versions of applications will be included in creative cloud. Or will there be a Middle Eastern Creative Cloud at an inflated price.
I think Steven is probably correct that Japanese and English won't be in the same version, however...
From the Creative Cloud FAQ
"In what languages is Creative Suite available?
"The Creative Cloud experience includes the Creative Cloud website, Creative Suite and other desktop applications, and several online services. When using the individual CS6 applications, members can select from any language in which each is available. Unlike owning the traditional licensed version of a CS product, Creative Cloud membership gives you the flexibility to choose whichever language works best for you in any given application.
"The Creative Cloud website itself is available in Dutch, English, French, German, Italian, Japanese, Spanish, and Swedish. Visit the tech specs page for information on language availability for other components and services."
- In CS6, you still can't install the J version and the English version on the same machine for the same version (without resorting to virtualization)
- Creative Cloud may not be available in all countries at initial launch (this is different from the set of available languages)