AMD need new architecture and they needed it when maxwell launched 5 years ago.Not even better 7nm proces can save them because radeon 7 didnt even beat 2080TI(and it should because it is on new node.Something like 7970 vs GTX580.Its like 7970 will only compete with GTX560-second tier GPU.Thats how AMD is behind today)If they will keep using gcn they will never catch up nv again.
They are actually ahead and Turing is more like AMD's architecture, than the other way around.
If you compare RX 580 and GTX 1060 6GB, you'd see that the RX 580 wins in almost all new games. RX 580 is about 15% faster than the 1060 in Wolfenstein 2, same in Doom and it generally beats the 1060 6GB is pretty much most DX12 games, as well as the newer DX11 games.
Turing architecture has been iterated and designed more like AMD's arch, as it is more efficient and better at processing low level api's. The miscalculation with AMD is the speed of adoption of DX12 and Vulkan. They thought that a lot more games would be DX12 or Vulkan and that just hasn't been the case. As you can see Turing processes low level api's much better now and a card like the RTX 2060 beats even the 1080 in games like Wolfenstein and some better designed DX12 games.
There is a huge case to make for Vulkan, both Doom and Wolfenstein 2 are running extremely well, much more than most other games, yet devs are still using DX11 and older engines.
Also Nvidia's Turing architecture is basically a slow reiteration of their 10+ years old GTX 200 architecture, which was their first unified shader architecture. Just because AMD has kept the same codename GCN vs Nvidia who change the codename doesn't mean shit.
Vega failed as a gaming card because AMD wanted it to serve dual purpose, to be a compute monster AND gaming card, so it was big and packed with compute power, but that didn't make any difference in games. Truth be told DX12/Vulkan games are heading towards being more compute centric and having this general unified process, even things like raytracing are designed as such, but it's a slow process, mostly with game engines and GPU devs unwillingness to go all out, as that would mean having worse performance in DX11 titles.
Thing is it took 1 year for Wolfenstein 2 to pack some of the technologies used in Vega and utilize them. Barely any other game takes advantage of the full assortment of features Vega offers and if they did Vega would perform at least 10% better across all DX12/Vulkan games.