If Barts is a mid-range chip, it should use the mid-range x770 moniker, not the high end one. It's not just about how fast it is or how much it costs, but where it fits amongst the lower and higher range products.
It's not just that easy, they might look out for naming scheme to enemies lodging ... or if i might axsk should gtx450 be named gts460 cause after all it's just "mainstream version" (gf104) of their infamous big bro gf100
Every gX4 chips in recent past (since g84) carried only "gts" or even measly "gt" branding 8600gts/gt-9600gt---gt240/340 (if we loosely assume gt215 to be gx4 part)
Anyhow, i smell Bart should be willful participant to 28nm dumb shrink test with die size <130mm2 in June next year, so they'll need some spare naming space to offer something in reasonable HD6700 space ... because for the sake of marketing (hopefully) they couldnt sell 130mm2 chip for 151-200USD and retain HD6800 name. Only weird thingy is that they still need to cut off "two non-working pipelines" from fully working 1280SP on RV940 chip, which probably, just as RV770 and RV570 before it, will came out to be healthy die in 90% cases.
Only bad thing in this scenario is that HD6700 will be yet another bw limited 128bit part with maybe 6Gbps gddr5.
Lets hope that nVidia will soon introduce speculating gtx475 cards on fully working gf104 chips, and that amd will be forced to abandon 6850 with laser-cut 160SPs in favor of fully working HD6870
And renaming pricey HD5770 to let say HD6670 along with sizable price cuts to 100USD would be much appreciated especially if they could be easily paired with older 5770 without bios xflash and similar fuss. Renaming it just for the sake of renaming wouldn't be good. And yet better would be that they simply cut down prices and retain original name.