The chips are huge and numerous & you would have to boostrap a market to compete, that's hard. Technically it can be "duplicated", but in the same sense that Ap

The chips are huge and numerous & you would have to boostrap a market to compete, that's hard. Technically it can be "duplicated", but in the same sense that Apple can make a state of the art processor better than Intel: you have to assemble a big first class team, a shitload of money, and persist during 10 years. If you want to compete on a similar field as mainframes you also need extreme reliability, and that's even more expensive to design. If you relax the requirements and make some quite special purpose hardware arguably it should be "easy" enough to make some fast I/O that can handle volume; but then your market will be small, niche most of the time.