They have been working on the photonic chips essentially forever. There is hope that the breakthrough will come when transistors no longer advance, because they must. In addition to scaling clocks to terahertz the photonics don't produce anywhere near as much heat so you can stack them like the layers in flash memory. The cores will likely be very basic risc cores from the first.

Quantum computing is rather specialized. Non Von Neumann architecture. Unlikely to enter mainstream computing any time soon but irreplaceable for the applications that need it.