Ultimately, any where could be the theatre, although you seem to be hinting that some geographic variation is desired. The idea here is to put you inside a very realistic simulation of the F/A-18 and then have you fly a diverse set of missions against realistic threats. It doesn't really matter where it takes place, just how well it is all put together. By selecting a known theatre it is easier for the player to relate and be immersed. As well, a known theatre has known threats and allied forces, which can make it easier to model and plan a realistic campaign. If Libya is selected, there would be some divergence from the ground truth to introduce a higher air threat. Regardless, the experience should rewarding to the player, and this is just the starting point.