I think it could have worked had it been shot and conceived that way for the film, but it wasn't, and there's really no way to change it now that the Dr. M ending is in place.
Frankly, to me, the image of millions of dead, mutilated corpses strewn about New York is far more terrifying than an empty, burned hole in the ground. But I don't mind the movie's ending, and it's not like there's anything I can do about it anyway.