Rumored release dates were as follows:
Vega 56 - 30th July, 2017
Vega 64 - 30th July, 2017
As with past **leaked*8 release dates in recent generations, release dates and perfomnce is expected to be be behind expectations.
Rumors of the RX Vega cards were between $599 for the top GPU and $399 for the basic Vega. The $999 pro-level Frontier Edition delivers between GTX 1070 and GTX 1080 gaming performance, but AMD was targeting ~GTX 1080 speeds for the RX Vega.
It's was suggested by an industry partners that the RX Vega would be a ~300W TDP for the reference card.
http://www.trustedreviews.com/news/amd-vega-specs-performance-release-date-technology-explained-2993156