Check out the section "Operational Cultural Information" on your MOL account after you graduate TBS. It will be there. I got assigned the arm pit of the world... I mean East Africa. But yeah, we are supposed to have to take PME along with EWS in our region to become subject matter experts in that part of the world. We'll see if that really happens.
FWIW, the Navy is doing something similar but at field grade and higher. About five years ago the Naval War College broke up the masters degrees into several geographic and functional "areas of study." The program had already been that way for a long time but the difference is that after a cutoff date (~5 years ago) people have to choose a minor, in addition to getting the old JPME + masters in international relations. The minor translates into a sub-specialty stamp in the service record.
Hedging our collective PME bets I suppose, like putting lots of chips on some numbers but at least one chip on every number on the roulette table.