Well remember it's still officially MSRP $2000, these are just temporary sales that I assume will stop once the 70D actually gets announced.
I'm not sure the 70D is really gonna put any pressure on prices for the 6D, just two different price points honestly. The list price of their xxD line is a good $1000 cheaper than the xD line (60D listed at $1099). Even if the 70D turns out to basically be the 7D in terms of AF, etc...do you think the 7D is influencing sales of the 6D? The informed consumers are looking for different things (landscape v sports/nature), and the uninformed are just looking at the price tag, which is 40% less with the 7D.
If the 70D came out with some amazing new sensor that was comparable to full frame....then maybe