It would be nice to have an open source reference implementation to demonstrate how the APIs should be used.
The implementation would not have to be performant, but open and generic would be the goal.
Such an implementation would also shift the inter-operation problem from the domain of code and linking somebody else's executable into very visible space, such as UDP sockets. That would make the integration completely vendor-agnostic if both parts participate.
Invoking closed source 3rd party library from competitors linked into one's code may raise questions about proper support and responsibility in case of problems.
Reference implementations also help with sanity-checking of implementations of the specification.
VSF may also try to encourage vendors to open source their implementations (or relevant parts of it).