If talk about 9070xt being on par with 7900xt turns out to be true, then I don't think it will be that low.
The reason I think so is because they don't want to end up affecting the sales of their remaining stock of 7900xt. If it is cheaper than the 7900xt but offers the same performance, then no one is going to buy the 7900xt unless its price is reduced to below the 9070xt. I also assume that they are going to continue making the 7900xt until their UDNA series comes about.
If their intention is to phase out the 7900xt and have the 9070xt replace it, then the 9070xt would likely also take up the 7900xt pricing tier (ie 700 ish) in the hierachy.
In any case, I don't expect below 600 usd for it.
But when considering what green team is offering, <=500 does make more sense as you mentioned.