Although I'm specifically interested in the likely economic consequences of implementation of an official world auxiliary language, since this is only theoretical, I'd like to know what have been some economic consequences, whether positive or negative, for those nations that endorsed a lingua franca and thereby opened themselves up to segments of the rest of the world (or conversely, I'd be interested in the long-term economic consequences for a country which, perhaps for anti-colonial reasons, rejected a more internationally spoken language in favor of a local one).
For this question, I'm less interested in lingua francas whose effect was primarily domestic. For example, with Modern Hebrew being chosen in Israel, or perhaps Mandarin Chinese in China to a lesser extent, the ability to speak a new official and universally taught common language did not open up the country precipitously to opportunities for communication with other countries.
Note that I'm not asking here about the economic costs of implementing such a language change.
No doubt, and as with free trade, all things being equal, a lingua franca would increase economic opportunities, whether in collaboration possibilities, education opportunities, etc., but, also as with free trade, a lingua franca might precipitously expose a country to competition in certain (intellectual) fields and thereby create resentment within certain industries which in turn led to protectionism. What experiences have been documented on this topic?
(Note: I can't create a "language" tag for this post, due to my being new here, so "free-trade" was the closest tag I could think of.)