Strongly agree with @codinghorror I think it is best to pilot the program in 2 locales for 1 month or so and then expand.
Hosting wise at Enterprise level we can offer multisite configuration so you are heavily discounted for multi instances. In a multi instance setup we can control some site settings that cut across all sites.
Keep in mind, Discourse is not localized to 40 languages, so you may have to add in some translation work.