Not even two days have passed and EK Water Blocks is already announcing that they have watercooling blocks for AMD's latest Radeon R9 280X cards. Apparently the fact, that 280X is almost identical to the Radeon HD 7970 GHz Edition, make the old EK cooler compatible with the new cards.
Since the Radeon R9 280X is based on the exact same chips like the HD 7970 GHz Edition as well as the HD 7950 GHz Edition, which is the Tahiti XT, AMD didn't have to do any modifications to the reference PCB design at all. This in the end bears the consequence that EK Water Blocks now has "old" coolers which can simply be relabled to match the new cards naming convention. Furhtermore even the full-cover blocks for ASUS' R9 280X DirectCU II and Matrix cards are identical. And yes, you're guess is correct, the R9 280X DirectCU II and Matrix feature the same PCB like the 7970 based cards.
Additionally the guys at EK Water Blocks are now working on yet another full-cover block which will be compatible to the upcoming Radeon HD 290X graphics cards. This card is scheduled to launch on the 15th of October, 2013.
Source:
EK Water Blocks