Imagine if all the wallets on Earth of every coin on Earth had one more button in them - an "Escrow" button, which would be as natural to any wallet as the "Send" button now.
If blockchain can safely swap values between addresses in a trustless system, why don't we use the same mechanism to safely escrow the values in a trustless system to safely meet the conditions of the swap? ... and then we don't need exchanges any more. Then you have a total peer-to-peer society simply because every single person or entity on Earth could now safely agree and then safely swap values between them.
All we need is just one additional layer - an escrow layer- easily available for any blockchain. Something like TCP/IP is to the internet Plug-and-play sort of thing.
We need a PROTOCOL not just another app . ... and the REAL market, where anybody with a phone is a market player, will take care the rest