AI does not "emerge" spontaneously without somebody building a learning ability, or an evolution ability. Both require a mechanism to determine if an outcome is "good enough" or not.

For us humans and predecessors that mechanism was exposure to an environment that would kill off the "not good enough".

What environment that can intervene, or what learning mechanisms would a block chain have if not some that were designed in by humans? Currently, there are none, so the chance of "intelligence" (the ability to solve new problems without instruction) emerging from a block chain is rather slim.