Interoperability needs to be understood alongside two vectors: a) between consensus computers and b) with the real world of law and regulation.
Consensus Computers need to talk to one another, speak the same language, share the same characteristics and modularity stack-wide, see previous posts here and here. Consensus Computers also need to interact fully with current legal constructs. What a CC shows ownership-wise needs to be fully compatible with how ownership is construed in the real world.
Hence, I view interoperability needing to toe as closely as possible to a “magic” optimal line. Too much focus on technology related interoperability oversimplifies the problem and risks pigeoning Consensus Computers to a restrictive “internet of value” mindset. In other words the transfer of ownership is not equal at all to the transfer of data. Transferring data is easy. Transferring ownership is eminently complex. Technology protocols cannot be developed in the abstract and without tie ins to the real world of law and regulatory oversight. Protocol design needs to incorporate in a very granular way real life legal domains. Therein lies the real power of true interoperability.
As such, any interoperable protocol needs to be developed with a careful consideration of both vectors.
Interoperability Optimal Frontier: