All the hard bullets are already handled by existing math (codecs), protocols/libraries (reliable networking), operating systems (hardware support), etc., no?

All the hard bullets are already handled by existing math (codecs), protocols/libraries (reliable networking), operating systems (hardware support), etc., no? This is not to say it is easy at all, of course; there a thousand things to do to implement it, but I think other fields face similar constraints, like videogame engines and distributed simulations.