If it's coming this soon I don't think it'll be touching Radeon 7's space for now, the only architecture they have that's notably out of date at the moment is Polaris (It's technically been 3 years since AMD had a new low-mid end architecture), the easy guess would be a ~40CU and a ~20CU die again, with very loosely about 70% and 35% the performance of Radeon7 respectively, presumably closer to 50% and 25% of the price (RX680/660 with a cut down version of each below). Presumably the higher end models/VegaII replacements are closer to 12 months away.
Edit: To be honest I wouldn't be surprised if they skipped straight to 700 to keep up their shoving 7's in absolutely everywhere.
I'll believe it when I see it.
Quote from Gibbo at OCUK;
'Yes Vega is EOL, AMD have now sold everything they built, unfortunately they have no replacement due on the £300-£500 bracket until the VEGA 56/64 Navi Performing parts due late Summer.
But that is why they informed us to stock up as much as possible on VEGA 56/64 as going forward for next six months or so there shall just be 570, 580, 590 and Vega 7, so any reseller who did not stock up on Vega won't have any thing from AMD to sell in the £300 - £500 region.
Though in fairness Vega 56 was never supposed to go sub £300, we just made it happen because Vega 56 at under £300 impacts 590 negatively and 590 is priced correctly as is 580, so Vega 56 needed lifting in price.'
So Navi replacing vega 56 and 64, as per rumours.
High end Navi is clearly at least a year away.
I'm a little confused, Vega 7 is competing with the 2080 which puts it a decent chunk faster than Vega 64 but by the sounds of it Navi will be replacing Vega 7 with roughly the same performance bracket.