Middlemen are not indispensable - they need to justify their existence not others to justify their absence. The whole point of cutting out the middlemen is to force them to go from a parasitic role to offer some sort of actual utility for their price.

If the middlemen have something of value to offer they have little to fear - just someone to buy gasoline by the tanker for instance keeps gas station middle-men safe because they provide both a workable connection between logistics of the very large production and consumer scale amounts - in addition to the distribution.