GPUs are not like CPUs,they live and die on game support and drivers. Once companies move to new designs,they are not going to prioritise old ones. The issue is that raytracing support is a big generational change,and as much as I think its a bit overhyped IMHO,its going to be where the future lies,especially if a GPU is being kept for 5~6 years. The last change this big was programmable shaders in DX8/DX9.
On the AMD side,the uarchs which were in consoles,ie,GCN1.1(Hawaii) and GCN1.3(Polaris) have aged very well,and GCN1.2 and Vega,seem to be having problems now. So I see RDNA1,probably starting to fall behind RDNA2 as the consoles will use it - most major PC games are developed for consoles now.
With Nvidia,they are certainly pushing RT and upscaling too. Any major hardware changes here,won't put Turing in a good light. So,say Ampere does RT twice as better as Turing(rumours say more),an RTX3060 might end up being as fast as RTX2080TI once you start using RT,and RT performance is something Nvidia can probably scale up more easily than rasterised performance.
With the RDNA2 based GPUs,there are huge changes over RDNA1,which were highlighted in the PS5/XBox Series X launches,ie,added RT support,but also VRS,and various other technologies. Turing has a degree of these technologies,but especially with the more mainstream models,lacks sufficient processing power. We already have pictures of the coolers,and other leaked information on Ampere. Latest leaked information is that Ampere and RDNA2 launched will be over the timespan of September through to November.
I have a Pascal based GPU now,and if it went kaput,I have an old GTX960,I would rather struggle with that for 4 months,then get one of the current GPUs.
The issue is that Turing was a poor generation in terms of price/performance as Nvidia jacked up prices,so you essentially had no change in price/performance over Pascal. When AMD released the RX5700XT it helped pushed prices down a bit,but it's not been a great generation at all. In fact IMHO,one of the worst in terms of generational uplift for years.
For example the RTX2080TI was 25~30% faster than a GXT1080TI for 50% increase in respective launch prices. Compare that with the move from Maxwell with Pascal which was massive. The GTX1080TI was 75% faster at qHD than the GTX980TI for a 10% increase in launch price. AMD didn't bother releasing a flagship RDNA1 GPU. Ampere and RDNA2 should realistically have better generational performance jumps.