Number of transistors is not that important, what's important is actual size on the same process.
RDNA3 CU is supposedly a bit smaller than RDNA2 CU on the same process according to SkyJuice
Then this is from Locuza. If N5 provides 70% better scaling, then without It, It would still be 50% denser.
View attachment 75410
There is no reason to use RDNA2 when RDNA3(+) has comparable size on the same node and is still faster.
Steam Deck has only 15W power budget for SoC and that SoC is 4C8T Zen2; 1-1.6GHz 8CU RDNA2 IGP using N7 process.
16-18CU RDNA2(3) is too much for N4 or N5 process and 15W.
Phoenix is using N4 instead of N7 and still kept 12CU IGP, only boost increased by 25%.
They can either keep 8CU and significantly increase frequency to 2-2.4GHz(+50%) depending on V/F curve or keep frequency but increase CU to 12(+50%).
Phoenix reviews will show us how high It can clock at limited TDP with 12CU.