NDa doesn't mean no launch. NDA didn't mean no launch for nvidias 1080. Unless that presentation wasn't considered a launch.
NDA just means the sites cant say what AMD hasn't said. So it would be left to AMD to actually do the revealing of information rather than having sites taint their message with opinion. They could be launched today, or e3 with reviews out 29th, similar to the 1080 launch 11 days before nda was up for reviews.
Can't really tell when AMD plans to "launch" the cards. Launch in quotes because, following nvidia's example, there doesn't have to be stock to sell. When we can expect proper details is the question.
The 480 would be decent if AMD is more able to reach their theoretical peak. 5.5tflops should be faster than a 980. But AMD has needed dx12 to make use of their power so far. A 480x should be 1070 level or close in dx12 at least. Probably faster with async compute. If they planend gddr5x for the 480x and nvidia is holding them up there (with micron), then 480x might come later.
Ideally there would be three SKUs above the 480 (480x, 490, 490x), but thats just wishful thinking.