AMD hasn't gotten to the point where they're competing with themselves. Definitely not in GPUs, and not even in CPUs. They didn't hesitate to launch a faster product in April 2018 at a lower price point than March 2017, despite Summit Ridge inventory still being in the channel.
If you look at sale figures from Mindfactory (since other retailers don't provide such data), AMD is easily outselling Intel in retail processor sales.
You did point out that 2rd gen Ryzen is cheaper than 1st gen Ryzen, but that's only in response to Intel, specifically Coffee Lake.
Core i7-8700K has two fewer cores, but it has higher clocks and higher IPC, which allows it come uncomfortably close to the Ryzen 7 1800X in multithreaded scenario (which is AMDs' best scenario)
Ryzen 7 2700X was only a minor step up from the Ryzen 7 1800X.
With Core i7-8700K at $359, Ryzen 7 2700X would be a tough sell at $499.
So let me make this clear, AMD didn't lower prices because it wants to, but in response to Intel.
If AMD can make a processor that match the Core i9-9900K, it wouldn't be lowering the price. Expect it to be at least $329.
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Similarly, with graphics:
Don't expect AMD to seriously slash prices, except in response to NVIDIA slashing prices.
That defines prices, either from the bottom up or the top down. AMD's current top-of-the-stack MSRP for AM4 is: $330. Expect it to go up this year with Zen2. Stuff that is not at the top of the stack will have lower prices than the halo chips.
The point still stands:
If AMD can make a processor can match the $488 Core i9-9900K, why would AMD sell if for less than $329?
That is true . . . higher than $330. For the halo chip. 8c isn't halo anymore.
...and why does that matter?
I would agree on the 56CU rumour anyway.
...and pretty much the rest of it too
Those prices are close to MSRP. 1660TI MSRP was $279 at launch. 2060 FE was $349. AMD still has to deal with street pricing. Assuming prices on the 1660Ti and 2060 don't move much, Navi for $250-$300 gives AMD a chance at a winner, IF it beats the 2060. If it doesn't then I don't even know what to say.
So what?
Those prices are still cheaper the cheapest GeForce RTX 2070, cheapest GeForce RTX 2060, and cheapest GeForce GTX 1660 Ti.
...and, of cause, at some point, Navi would go on sale and be cheaper than its MSRPs