Blockchains don't solve the trust problem at all. Except if none of the trust problems you have interact somehow with the material world
That's the only thing blockchains solve is the decentralization of trust. Oracles provide a bridge, and it is possible to make trusted decentralized oracles.
There are plenty of solutions to middlemen. Usually they exist not because of technical limitations but because of other reasons (see car dealerships).
I guess I'm just not creative enough to think of what that might be, if not money.