Pretty sure they have things working for at least some games and could have easily provided some benchmarks that would have given us an idea about its performance. I'm sure running two Vegas in crossfire wasn't just for fun - it basically sent a clear message that one Vega cannot run the game at >60fps at 4K, which means it is slower than the GTX 1080 Ti (AMD sponsored title).
Which is an oddity as we've already seen single Vega's running Doom and Sniper Elite 4 at 60fps, 4k. This new demo doesn't make any sense, Prey has similar performance to their other demo titles.
Pretty sure it's only going to be clocked lower than the consumer Vega, so overclocking it should provide a decent idea of how the consumer cards are going to perform (drivers are probably different as well, but with some tweaks it should be possible to make the system think you are runnin a consumer Vega card).
That's what I think too. The wait is on... again.