VW Interoperability -- client or server side?

Suppose I work for large corporation A. It uses a virtual world from ATech. Suppose that local government B uses a virtual world from BSys. Suppose that we want to connect these virtual worlds, say for doing a training exercise. Perhaps A has a large chemical plant, and B wants to figure out how to fight fires in the vincinity of that plant.

Current thinking about how to integrate virtual worlds involve talk like a "multi-protocol client." However, that doesn't solve this problem -- for a simulation to make sense, both servers will want to see the same data, although they may divide authority of various entities.

Would it make more sense to start out interoperating by connecting servers to each other, instead of some kind of multi-protocol client? It ought to be easier to bridge to different simulations, on the server side, and use the respective clients for the respective users. In fact, this has already been done, in the military, for a long time -- airplanes, ships and constructive entities all can share a battlespace. Why not on the civilian side?

The architecture would then look like:

The nice part is that the graphics, animation, and other client problems don't need to be solved in this approach. Only the business of sharing what's essentially telemetry data between the servers is needed -- and a shared view of the terrain ("game level") that the simulation happens in.