By now, it would not hurt 600EX sales that much, since many who want and need them have purchased already.
I doubt it because many people will have held back purchaising *more* 600rt because of the price and the expected 430ex successor - once the price drops a bit and there's no telling when and if a little brother will arrive, many people will "bite the bullet". I know I did.
The current 430EXII will continue to sell in large numbers probably for years, I suspect it outsells the 600EX-RT.
And there's a reason for this - people buying a 430ex2 like I did back than use it on camera for direct flash or bounce, so weight and size matters. Once you get the flashes off camera which is the whole point of the rt system, these factors don't matter that much anymore, but power and recycling time do - so the advantage of a little rt unit is diminishing to the targeted users, at least for me.