I'd also say that personally speaking, I don't have any attachment to East Continent. I've hardly ever played there and for me BM is bound up with other continents. Plus the geography of East Continent sucks. So a complete reset to one new continent designed properly (with a goal of moving to a dynamic map over time) would work best for me - but since that's probably not practical I'd rather see all continents closed (except EC and the Colonies and maybe War Island) and a strict two characters per continent cap enforced. The increased population density would make things more interesting for the time being - especially with the influx of refugees - and that could buy the game time while a new map for East Continent, which included some sort of frontier and ideally the ability to be made dynamic, was worked on.
I certainly think that the best mechanic of M&F is the dynamic map and if that alone could be incorporated into BM somehow (with AOW graphics) then that would be awesome but I doubt it'd be technically feasible.
You are right, it is not technically feasible in any time frame available to us. M&F's mapping system is based on OpenLayers, the game itself uses the Symfony framework. While these utilise PHP same as BM, they are so far removed from the BM implementation that you would basically need to rewrite all of BM to integrate them.
