Sadly, given how few people even know about the game, I wouldn't expect a huge number of sales. I bet a lot of mainstream gaming sites/magazines won't even review it when it's released, and it seems to have approximately zero marketing budget, instead relying entirely on word of mouth. Besides, very few people are actually interested in space sims, especially one as hardcore as Elite. Please do not compare with the old Elite games' performance back in the day, we all know the gaming scene as changed a lot since. And finally, a lot of people serious about buying the game have already done so by backing it, so I'm not sure how many more potential buyers this all leaves...
Let's be realistic, guys, ED probably won't sell tons. People talking about several million sales are simply daydreaming. Games like GTA, FIFA and Call of Duty sell millions, and that's because 1) they are well established franchises (the last Elite game was 20 years ago, young gamers don't know about it) 2) they are released on PC as well as consoles, and actually mostly sell on consoles 3) their genres are very popular and 4) their marketing budget are at least ten times the entire budget of Elite Dangerous. ED can never hope to compete with them in terms of sales numbers.
What we can do is spread the word and try to show it to as many people as possible, as it's surely an impressive game. I think it's biggest chance of success will rely on Oculus Rift ; by the time the consumer version is released, ED will probably be the best and most impressive game available, so some people could by it without being into space sims at all, just for the experience or to show their friends...