10 teraflop is achievable on the current size and power tdp for APU. Because it will just slightly more 44 cu or 48 cu to achieve 10 teraflop. The problem is when it will targeted above 48 CU (56 to 52), because it size will be more than 420 mm^ .
The problem are we still don't know what manufacturing process Sony and Microsoft will use for their APU. Will it be 7nm or 7nm+, also the final APU chip size for both. I bet if they are willing to lose money on early release year, they can easily achieve 10 to 11.
At the current progress actually RX 5700 Xt already slightly more powerful or on par with RTX 2070 on benchmark , the final chip for PS5 according to leak are close to RTX 2080 in firestrikes benchmark. I can see 2070 are hit the mark, now i wish they can push more to at least more closer to RTX 2080. So by the end of 2020 PS5 will compete with RTX 3070 and not with mainstream GPU RTX 3060. unlike PS4 that competed with GTX 660 (Nvidia mainstream GPU )when PS4 was released in 2013.
You need to stop looking at PC GPUs and start thinking about what Sony and Microsoft will actually put in their consoles. It's absolutely irrelevant what Navi is capable of, what matters is what cut down version of it they will put into their consoles to have an affordable product. I can't see anything close to 2070 unless they come right out of the gates with a $500+ Pro model.
You can do very simple comparisson actually to this gen.
March 2012 - HD 7870 (which is, more or less, what's in PS4) - 175W - $350
July 2019 - RX 5700 - 180W - $379
That would put PS5 at $399.
If there is some additional hadrware block for RT, that would be somewhat decent, though still pretty weak for proper transition to 4K.