It's going to result in a substantial uptick in performance per teraflop either way... I would not be surprised to see a 50% performance uplift over the RX 590."
Even without any architectural improvements, we'd be almost there already from just the higher clock speed and 4 additional CU.
In fact, if you just make a simple CU*clock speed calculation, you'll get actually very close to Vega 64 (air) at boost clock, and still surpassing Vega 56 just at gaming speed. So without even any RDNA improvements, it's sitting right between Vega 56 and Vega 64 in terms of performance and far above RX 590.
So yes, I think Navi will replace both Ellesmere (RX 570-590) and Vega except VII. Baffin (RX 460/560) and Lexa (RX 540-550) are probably still getting used as low-end/entry solutions. Especially Lexa, as it just months ago finally replaced the dreaded Oland chips (and the age-old cap verde chips in mobile) in mobile and entry-level desktop OEM.
And I would be delighted if they could adapt it into a high-end Laptop GPU. It's high time AMD gets back into that market.
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454
The Steam/GOG key gifting thread: https://gamrconnect.vgchartz.com/thread/242024/the-steamgog-key-gifting-thread/1/