I'm not certain how anyone can claim a delay unless AMD themselves stated when the product would be released. You don't get to claim a delay from some 3rd party source that claims they heard X Y and Z about release dates.
The 580 is 500 bucks. Is that worth it? That's your call (yes, you). It's the fastest single GPU card out there right now, and you have no choice but to pay the price premium if you want that performance. I don't think anyone in their right mind can say that it isn't a decent/good improvement over the 480. It is, objectively (measurably) so. If you don't think it's worth the price, don't buy it. Simple, no?