And pretty much all those cards run on 40 nm technology, the advantage of a new lineup would mean better cooling and improved energy consumption while generating more performance with each model. ATI has progressively brought out new sets that are improved in both power consumption as well as performance over the last few years. I remember the early HD series of cards, the 3000's and 4000's were not really that great but the 5000 series really became the dominant line of graphics cards. Nvidia has been behind in this regard, their early Direct X 11 cards having severe heating problems to the point where you could fry an egg on them.
I would assume the 7000 series will start out with early models being slightly better but more efficient then their 6000 series counterparts.