Some unlikely 2021 predictions

There's nothing inherently superior about Arm or RISC-V (or even x86); CPU cores of equivalent performance require about the same overall internal complexity (and transistor count) and therefore cost about the same amount of money to develop and manufacture. Of course, it helps to re-use portions of previous designs (and their test suites).

In order for developing your own CPU core to be economically feasible, you have to have an astronomically high production volume to make the NRE cheaper than licensing an Arm (or one of the higher-performing RISC-V) core. Only a handful of players have this volume, especially on the high end.

Meanwhile, the rest of the SoC will cost about about the same amount of NRE no matter what the CPU core is, and of course the actual fabrication costs only depend on area/yield. (The actual CPU cores are only a small portion of a typical SoC's area/complexity)