I think regardless of how big the maps are, the same type of hordes will still be common place.
Maybe not right after a reset, but once the tide of war starts going into a particular country, the boarders get smaller and the hordes go to the boarders.
Yes, there will be a few people who strike into the undefended areas to try and sneek a few quick captures, but all in all, it will be a big gangbanging.