If TSMC 28nm process dont have problems then we will not see a pipe cleaner product and we will have a High End card release after September/October.
This logic doesn't make sense.
How could AMD know in advance whether or not TSMC will have any unforeseen problems with the new 28nm process? I think the obvious answer is that you make a pipe-cleaner specifically because you do not know what the problems will be.
I'm not saying that AMD will absolutely release this sort of pipe-cleaner product first, but if they go with a high end card first, then they are deciding to take a risk/roll the dice on the process. The gamble may pay off, or perhaps they know that they will have an 'x month' lead on Nvidia, which, regardless of how well they have the process nailed down, will give them a big enough lead to do the first gen 7xxx series, and then do a slight re-spin to fix whatever problems they uncover in the process. No one can know at this point.
Not even AMD could have known in advance that the process would be smooth sailing, or flawed like 40nm was. Whatever taped out a few months ago, the decision to make that GPU was made months before any kind of working silicon would have been available. They either decided to gamble and go big, or play it conservative.
Honestly, they'd probably make more money by making the so called '7770' GPU, because it could probably sell for $170, and cost them far less to make than the 6870 does, leading to bigger margins.
A theoretical HD7750 832 SP gpu for $140 would be an amazing value for that price point. You'd see them all over the place in prebuilt computers. Also sounds like something Apple would put in their Mac Pro line.
Assuming they switch over to VLIW-4 for their whole line, top to bottom, I think a mainstream GPU launch makes a lot of sense to start with. Its where they would build the most market share, and mind share.
Offering a good performance at a great price. It would probably perform to about 560Ti levels, and be able to destroy the 560Ti on price.
The big question in this is how far out is Nvidia's next GPU line.
Unless Nvidia breaks from prior form, their first GPU WILL be the top end behemoth GPU, so if AMD doesn't expect that until feb/mar, then they probably have plenty of time to launch the mainstream product first, and go after nvidia at the top at a later date.
We mostly talk about the 69xx series and the 570/580's, but the reality is, that the vast majority of people won't ever buy that expensive of a GPU. AMD probably would want to grab as much market share as possible with a outstanding performance from a midrange GPU.
Cayman die shrink will probably be the 78xx, and something new and potentially very powerful will be the 79xx series.
7970 performance would probably be around 80% more than a 6970 - nearly 6990 perf
7870 performance would probably be around 15-20% more than 6970 - approx 570 perf
7770 performance would probably be around 15-20% more than a 6870 - approx 560Ti perf
The spot the theoretical 7770 would fill, is also where AMD is the weakest right now. They are using a rebadged 5770 for that target. So launching the new GPU there makes sense.