There is no reason why you still can't continue with the map, even if a large part of it is gone. What is done is done. End of. True it won't be as big as what people may have hoped the final result would have been, but there is no reason at all on why you can't stop the project. I have liked from what I have seen from the screenshots, but so much work has been done on the map, you might as well finish it off, so that the rest of us can at least have another great map to play on.