If you have trouble opening ports between companies, you shouldn't use a Blockchain at all, since Blockchain is a decentralized peer to peer protocol.

this statement is so flawed, there is no such requirement in ALL public blockchains. at most you can say is this is true for private/consortium blockchains, even that is terribly flawed since even PBFT does, in theory, allow up to 1/3 disconnected peers. 

you can never build a consortium while expecting everyone will open firewalls to each other, especially for international projects. it just can't be done, period.