I think a lot of people will initially race change to worgen or create a worgen druid just simply due to the fact that you actually after 6 years have an option to do so. Right off the bat you are obviously going to personally notice worgen over night elf simply because it's new and sticks out in your mind more. Just due to that, it will "seem" like there are more worgen druids. Overall though, I think it'll be about even the entire time.
I'll be sticking out as a night elf on my druid main forever because I like them. I will be making an alt worgen druid just to do the starting zone because I have every class but warrior (and I don't want to play a warrior) that can also be worgen.