If (1) AMD taped out 7xxx a month ago, and (2) it turned out that A0 silicon was production-worthy, and (3) TSMC's ramp-to-production volume capacity was timed to support a Q2 launch of a high-volume 28nm part...then it would be technically feasible for there to be a Q3 (July-Sept) launch of 7xxx.
(but it might still be economically or logistically unfeasible owing to 28nm yields, price/wafer, and supply chain disruptions stemming from the tsunami/earthquake/nuclear reactor crisis in Japan)
If A0 silicon comes back and it is determined that a respin is necessary (or merely justified if they have time in the schedule, 28nm capacity timeline, etc) then you can add another 3 months to the iterative "while" loop, etc.