What if the 7000 series cards have a much better stream processor count?
Just like the 6990 has more stream processors than the 5970? Oh, wait, it doesn't.
Does any of us know what the 7000 will bring?
Nope. All we can do is analyze how previous generations progressed, and extrapolate from there. From the 5000 to 6000 brought about...no change in mining capability. It's highly unlikely the 7000 will be any different. AMD designed it long ago, long before Bitcoin was as big as it is now.
That's because both the 5x and the 6x are on 40nm thingamaboppers. The 7x are gonna be on 28nm thingamaboppers. The extra space can/is going to be used for stream processors.