Sounds about right. Although I suspect we'll see a 1600 MHz part. Been hearing that number often enough to suspect there's some truth to it.
So maybe something like this for a lineup?
Vega light - 1200 MHz-ish. 1070 competitor
Vega regular - 1500 MHz-ish. 1080 competitor
Vega heavy - 1600 MHz-ish. Not really a 1080 Ti competitor... but a way for AMD to offer a bit extra for less money than a Ti. Cherry-picked silicon.
Which goes back to Kyle's guess some time ago that the top Vega will probably be between a 1080 and a 1080 Ti.
Don't think we're seeing 16GB on a consumer card, though. Maybe for the professional cards (or a quasi-professional card offered for the 'extreme' segment, like Titan Xp). I'd guess 8GB is our top end for consumer parts, at least for now.
Yeah I'm kinda in the same boat you are, between 1080 and 1080ti performance sounds about right closer to the 1080 though from what AMD has shown so far.