VideoCardz spreads word that the driver files of the 17.3.2 release contain references to the Radeon RX 580, Radeon RX 570 and Radeon RX 560. The former two are basically rebrands of the Radeon RX 480 and Radeon RX 470, while the latter one is a rebrand of the Radeon RX 460.
This doesn't mean these cards will be exactly the same, they will likely have higher clockspeeds and perhaps lower pricing.