If there's any truth to this rumor, I think GPU nomenclature standards are about to jump the shark. According to VR-Zone, AMD is on the verge of releasing a new GPU code-named Tonga—and the chip is expected to replace the Tahiti silicon inside AMD's Radeon R9 280 and R9 280X.
Yes, we may be about to witness the bizarro world equivalent of a re-brand. Welcome to the twilight zone.
The report doesn't say much else about Tonga, other than that it will, apparently, be built on the same 28-nm fabrication process as Tahiti. VR-Zone's Chinese sister site, from which the rumor originated, claims the memory configuration "will remain at 2GB GDDR5." That looks like a typo to me, though. The existing R9 280 and 280X both come with 3GB of RAM by default.
In any case, VR-Zone Chinese is quoting a "reliable source," so there might just be some truth to it. Or, you know, it could be total nonsense. We'll find out in August, which is when the site says AMD will unveil Tonga inside the non-re-branded R9 280 series.