Are they planning to use basically the same architecture for 28nm?
Not a clue, people say architecture like theres a massive massive change between some generations and thats rarely the case. The 2900xt moved to fully programable shaders, but the x1900xt had already moved to be dramatically shader heavy design(cough, AMD are usually thinking ahead a little, though maybe TOO far ahead too often to reap the rewards of it). Its a big change but also, not that big a change.
Anything about 28nm is speculating, there was talk that AMD were trying to basically bring part of the next gen cards into current gen cards as a new front end but keeping the old shaders. That might very well be the 6870, while the 6970 ends up a shrunken version of their full next gen 32nm chip.
AFAIK there were two chips, Northern Island and Southern Island, one meant for 32nm, one for 28nm, afaik parts of(or maybe all) of the NI design from 32nm has been pushed into 68/69xx cards, I doubt anyone outside of AMD knows what changes they planned from NI to SI chips, maybe just a large bump in shaders, maybe not, maybe a massive redesign, who knows. I would expect at some stage, to move to a 384bit bus, no idea if/when gddr6 exists/will be available. They went with a 256bit bus for a 1120 shader Barts, they are supposedly staying with 256bit bus for a 1920 shader 6970, at some stage you'd think bandwidth will be an issue.
I think they've got a new shader design for 28nm chips. The 6 series are a "hybrid" between their next generation, and the Evergreen chips. They use the front and back ends of their new design, while keeping the shader structure of the evergreen chips.
By most accounts so far, and from the only thing Charlie has really been willing to commit to, this has moved to a similar, yet very different 4 way shader, if it ends up being true then the 6870 does look like a merged design, evergreen shader + NI front end, the 6970 looks like a NI front end and shaders, but at a dramatically lower shader count than you would have expected for 32nm.
If only it was that simple, selling more cards at a lower price eats into your profit margin as you have to pay extra staff hours for handling the cards through the pipeline, your more exposed when things go wrong i.e. a batch of faulty cards can potentially wipe out a lot of your profit. And a whole load more to it.
A lot of things you cite above had nothing to do with any benevolence but things like fluctuating exchange rate, component supply levels, etc. for example you buy a bunch of GTX260 in at a price and have them in stock theres a limit to how far you can manouvre the price on what you already stock, if the exchange rate then fluctuates newer lines can be purchased at a better or worse price.
SOrry but what has realistically any of that got to do with anything I said. The first paragraph is simply wrong, if you sell 2million cards at £100 profit at £300, or 500k £400 cards with £200 profit, theres more profit in the 2million cheaper cards, double infact. Ask ANY retailer if they've ever sold more £450 cards than they've sold £300 cards, even if price/performance was identical, it simply doesn't happen. Likewise in reality a £300/£400 card doesn't equate to £100 more in AMD's pocket, it equates to £100 more in AMD, AIB, distro and retailers pockets. 90% of the extra cost involved in selling more cards, is having a bigger truck, carry more cards at a time, at a lower cost per card in terms of delivery. Its also cheaper per PCB to order 500k rather than 200k, and its cheaper per memory chip to order 50k chips rather than 25k chips. A batch of cards is a batch of cards, if they fail they fail, the wafer costs the same and its rare for a "failed batch" to make it too market. The last large batch of effected cards I can think of where thousands of GF4 ti 200's from Gainward, donkeys years ago.
AS for benevolance, despite me specifically saying it has NOTHING to do with any good will, but purely business sense you again(as MANY Nvidia guys do) bring up the idea that AMD are just nicer as some kind of joke. Yet every AMD guy I know says , quite specifically, over and over, that its nothing of the sort, cheaper prices, more sales, more profit overall.
