They are already shipping the silicon. There is as much real estate in the GPU as in the CPU. They could drop the GPU and have 8 cores in the same diameter. There are a legion of other issues with that many cores, but die space isn't one of them.

make -j

Hopefully with an SSD but I'd guess it's still IO bound

Depends on the language I'm sure. Compiling C++ is definitely not I/O bound. I have a 14-core build system that achieves approx linear scaling speedup over my dual core laptop.

Not at all; I've seen parallel builds remain CPU-bound on 72-way and 144-way systems.

The biggest bottleneck tends to be linking steps and other serialized items. (And those are getting better too; gcc's current linker supports parallelization using -j, integrated with make.)