But you can't fit that "sea" into a processor core as a separate unit powered by unique instructions (like an FPU or ALU) because the speed demands the cache an

But you can't fit that "sea" into a processor core as a separate unit powered by unique instructions (like an FPU or ALU) because the speed demands the cache and ALU be there (or else it can't run at 3GHz any more). Once it's not that close it doesn't make sense to be on the same chip; maybe a neighboring chiplet. But anybody could do that.