Well, I don't think the numbers support Ebonheart Pact being at TOO big of an advantage over the others, or hell even at one at all. Its probably closer to pretty even honestly.
The problem is though, we don't know anything about racial perks or whatever incentives (if any) there is to be any other race, and right now we just have everyone wanting to be the races they favor most. Trust me, since its an MMO you're going to see a ridiculous amount of people choosing their race/faction over perks like racial abilities and stuff, because the majority of MMO players will min/max or take the most op thing possible for their build, and this will change the faction numbers for better or worse. If there turns out to be one racial that shines above all others(human and night elf racials in WoW for example), that faction will be the biggest.
edit: There's also what that guy above me said. The megaserver will handle all of it like I said in my first post, it'll just keep making sure you see pretty even numbers.