hehe, more like a 780gtx or a 880gtx knowing Nvidia, infact, I really wouldn't be surprised by that, its quite possible/probably AMD/Nvidia will bring out some low end or midrange card to test 28nm on not that long away, then high end a decent while after that. I wouldn't put it past Nvidia to call their new low end card a 630gts or something, then they'll have no excuse but to name the proper new cards 7xx.
We might see some 4770 type parts for 28nm, late q2, early q3, though we'd often have heard something by now. Full new high end by the end of the year most likely, it all depends on exactly where GloFo/TSMC are with 28nm. Supposed to be available Q2 or so this year and AMD rarely go into a new process without a "tester" card in the midrange.
Is TSMC delayed further, or have AMD decided to not bother with a tester card, or do they just not have time to do one. I'd think Q4 for the high end parts is a good bet, and we'll hear about anything earlier in a couple months.