No...
When the 5870 was released ( 23/9/2009 ) the exchange rate was $1.62 per £. Today is is $1.55 per £. Not really a huge difference. The major difference is with the base RRP: The price for the 7970 is $549, whereas the 5870 was (IIRC) about $399.
The reason for this is that, with the 5-series, AMD was more interested in acquiring market share than in short-term profitability. AMD knew that they had a 4-6 month lead on Nvidia, and that their products would be able to compete well with Nvidia's offerings for the following year. But most importantly, they had the advantage of smaller dies and better yields, and so aggressive pricing was a way to leverage their advantages and put Nvidia in a difficult position.
Now though, AMD have moved to a more general purpose compute architecture (as Nvidia did with Fermi), so they no longer have the 'die size' advantage. Also AMD may be aware that they will struggle to compete with the Kepler range once it is released. So the smart strategy, under the circumstances, is to make as many high profit-margin sales as they can for the limited time that they have the performance crown.
Once Kepler is released you'll see these cards drop dramatically in price, since it will need to compete in a "bang for buck" sense, rather than being a 'premium' card.
The one major thing you got wrong is die size advantage, everyone on earth is still expecting a 500mm2+ monster from Nvidia and AMD held the die size advantage with gpgpu features last gen also.
Keep in mind the performance/size of 6870/560ti, and the fact that, while people don't acknowledge it the 6970/5870 had a LOT of gpgpu functionality.
The card(when unbound by tdp) essentially on the stock cooler quite safely does the 70-80% faster, at the same die size.
Likewise the 480/580gtx are comfortable the same amount faster than the previous gen you'd expect despite moving to be a "general purpose compute design", while at the SAME die size.
Basically, gpgpu is more about getting it right than transistors or die size.
It's VERY likely that either both at sub 300W cards, or both overclocked to what they would likely launch at without a 300W boundary, that Nvidia's 500mm2 card is going to be fighting with AMD's 360mm2 one.
Die size advantage hasn't gone anywhere, AMD are either, taking HUGE margins and taking advantage of early buyers(or, should it be early buyers letting themselves be taken advantage of?), or wafer costs went up more than reported, and yields are ruddy low........... if its the former, which for me is almost certainly the case, pricing should improve dramatically when Nvidia have something competitive out OR 580/570 pricing tanks to the point people would prefer them.
if its the later........ I really don't want to know where the 500mm2+ kepler will be priced, if wafer costs and yields make a 360mm2 core/card genuinely not a rip off at £400+, then 500mm2 would end up, well...... scary places.