As 7800 XT is not EOL and 9070 is a step up performance wise I think $500 won't be hit, if they do they essentially end up killing of their own current 7800 XT.
As I am not privy to pricing as all my stock is owned at a dummy price so to speak, I shall take an educated guess as I have no insider knowledge on pricing and as such I am taking an educated guess and not in breach of any AMD NDA, so if anyone at AMD complains about my post, well look at the timestamp......
So my guess is as follows:
7800 XT is currently $429 - $499
9070 at best case no doubt $549 and worse case $649
9070 XT at best case $649 and worse case $749
The above is my educated guess, because also the two 9070 variants need a minimum of $100 price gap, anything less and everyone will just ignore the regular and only buy the XT version.
Personally I feel if AMD hit $549 and $649 they won't be able to keep up with supply they will sell like absolute hot cakes as there is simply nothing else available globally at the price point in volume, but once NVIDIA ramp up volume they may need to be more competitive.
Going forward once 7800 XT is gone and NVIIDA has ample stock they may need to tweak those prices another $50 down maybe at Black Friday.
Let us see I just pray AMD set an aggressive MSRP, but a realistic one which AIB's and Resellers alike can easily sell at and still make a profit.
Remember MSRP is always starting price for a base model so say a Sapphire Pulse, Powercolor Reaper, Asus Prime etc etc
Of course cards such as a Sapphire Nitro, Powercolor Devil will carry a premium!