I think we can safely assume the RPL i7 will be going up against the ryzen 9 12 core again as Intel will be increasing core counts. The ryzen 7 8 core would only just be able to match the Alderlake i7 assuming it gets around 40% ipc.
Nah.
AM5 has higher socket power spec so 16c parts can actually stretch their legs. If you allow a 5950X or 5900X to consume about as much power as a stock 12900K then you see 20% performance increases in MT production workloads. Considering the 12900K sits between the 5900X and 5950X in production workloads that increase means the 5900X can catch up and the 5950X has a 25% or so advantage on the 12900K at similar power levels.
With a 170W max TDP it means AMD can let their 24c (One will come eventually, may be a Zen 4 part to fight off RPL or may be a Zen 5 part but it will happen at some point on the AM5 ecosystem), 16c and 12c parts fly so I can easily see above average gains with these parts in MT workloads.
On top of that a 40% performance increase on average for low thread count workloads will put it a good 10% ahead of RPL (Napkin math time. CB single thread has ADL about 15-18% ahead of Zen 3, some tweaks to RPL p cores could see that stretch to 30% max so a 40% gain for Zen 4 gives it the 10% delta over RPL in low thread count workloads).
I think RPL i7 will sit between the 8c and 12c Zen 4 parts in MT workloads if that i7 has DDR5 ram and if it has DDR4 ram then it will be closer to the 8c part. I am assuming here that the RPL i7 will be 8p 8e and have similar performance to the 12900K at much lower power draw.
As for gaming I don't really see any ADL or RPL part competing with any of AMDs Zen 4 parts.
As for the Zen 4 stack. I expect at launch, due to high DDR5 prices AMD will probably only bother with the 8c, 12c and 16c parts. I could also see a naming reshuffle to make 8c R5, 12c R7 and the 16c the 7900 R9 leaving space for a 24c 7950 should it be needed and as yield and supply becomes more abundant.
For cheaper builds that is where Zen 3 and the 5800X3D come into play. I could see AMD positioning the 5800X3D as the ultimate gaming part with 5700X being a good workhorse that will end up being priced to compete with the 12600K. The 5600X and 5600 can compete with the 6p 0e ADL parts already so just price them competitively and let the cheaper motherboards reduce the platform cost comparison. Then the 5900X and 5950X get EOL'd as the kinds of users who would look at those parts would see a huge benefit going with a Zen 4 build. Also EOL'ing the 2CCD Zen 3 parts gives more N6/N7 capacity for the v-cache, Zen 4 IO Dies, N33, N31/N32 MCDs etc.