The solution is unfinished as reflected in the list of to do items. If you trust each other then you can just communicate the trade details however Centralized and Decentralized escrow are being implemented.
What a BS! Escrow (or whatever on its place) is the core of such system. Without one it is just another useless bulletin list. Hundreds, thousands already exist.
Next time when you start developing, begin with the core not interface.
The "core" is easy as I've explained but it requires consensus before time is put (wasted) into it. The hard part was implementing trading over decentralized networks securely, anonymously and in less than one second. No currently existing technology can achieve this level of speed in decentralized trading. Thanks for your input.