there is many things wrong with RoF (mostly because they are starting to sell it before many of the problems with it are resolved, and it has a very cumbersome and inconvenient online-only play mode), but i just noticed a few comments in the last weeks from its staff that they are planning to release a ww-2 sim next, and that they will do this "soon" (not in a few years, could be as soon as a few months)
right now they sell a game with 2 flyable aircraft only as a ww-1 flightsim, and they have completed the work on their scenery and grafix engine. to now create two ww-2 flyable planes and slightly change their scenery to suit the battle of brittain era would take them very little effort imo.
they also provided some degree of openness in their game environment where they want to get their customers involved in creating game objects and addon planes and scenery
oleg, you might want to consider releasing BoB sooner then later imo. RoF looks very good (probably not as good as BoB will be, but close ?), and if to many flightsimmers get distracted by it this could well take some of your customers away
your loyal supporters know you are working on a grand masterpiece that will set new standards in flightsim performance and features, but there is only a limited number of aviation fans out there as a customer base. the sooner you can releases your sim, the more wind you will be able to take out of their sails