I think it is going to be too late for a 500GHs device in late Q4
Well they have said that the chips are 500 GH, not the devices. Maybe they'll throw 16 of them in a box and charge 7k for it? Don't really see how they will generate much in the way of orders otherwise.
People don't realize that multiple chips make up miners. They need to be at the magical number of 1th per $1000ish or less to be worthwhile against any competition and longevity as they seem to be hinting at.
that would be great but is it possible?
Probably not. Silicon wafer's aren't that cheap. There is a production cost and @ 28nm unless you get a design which is significantly more efficient (GH/s per mm) you are probably looking at more than that just for chip production cost. Of course that ignores the BOM, assembly, testing, defects, profit margin, and amortizing the NRE.
Keep in mind that fixed costs are high but marginal costs are low, so once the chip is designed it's not THAT much more expensive to put 16 chips on a board than it is to put 2, or like Bitfury design a mobo that takes 16 boards that each have a 500 GH chip on them or something. Not that I know anything about the feasibility of scaling this type of technology from a technical standpoint... This is more of a guess than a knowledge-based opinion. Maybe someone more qualified than myself can shed some light?