I am in the same boat, I purchased an MSI Lightning 6970, and planned to throw in a second one when I'd tucked away enough money. Few weeks later they are all deactivated and out of stock.
After several phone calls and emails to MSI, I got an email from a sales manager telling me they would be available.
"1st or 2nd week of August they should be back in stock, AMD has a shortage of the high end GPU"
this would explain why shortages seem to be out across all manufacturers - so we should be seeing retailers with replenished stock quite soon.