Well there will be more players from D+ before that happens, so there will be more people to play. Once ME is released a serious modding community will develop, possibly including many people who will move from DE to ME. IV may consider adding more to MW in the form of more game modes* and sever options. *For example, they may make it possible to automatically go to another game after finishing one, allowing the winner to be determined from the results of a number of games and also making tournaments quickly and a lot easier to handle.
This is just speculation though. You are right in thinking that MW is the single biggest thing that the MW community is waiting for.