SoRecklessA lot of people are speculating that Vega will be the 500 series. I'm inclined to lean towards 490, as we're still very much in the RX 400/GTX 1000 series. I don't see AMD launching the 500 series to go up against the rumored 1080ti. But as always, we'll see.
MedionBethesda somewhat confirmed the R9 490x, it was listed along the GTX1080 in the requirement for their new high-res texturepack for Fallout 4, but was quickly removed.
Vega was also always talked about as something alongside Polaris.