I'd like to see a Multiplayer SDK, and then maybe 3rd Party Developers would have the information to develop dedicated server solutions. -- at least untill there is a change in the MP system, as new updates are released.
There was no Multiplayer SDK for FSX -- one reason being given, is that multiplayer was to heavily integrated with Gamespy, and hence could not be released by MS .
P3D does not interface with Gamespy, but despite that, I personally cannot see Lockheed "PRODUCING" or releasing any form of Multiplayer SDK. (one has to wonder just how much, (if any) of the FSX MP system was even formally documented outside of the source code !!)
Even though I would be overjoyed to see a P3D Multiplayer SDK, I won't even waste my time asking if one might be released.
I think I stand more chance of winning the MegaMillions Lottery, than seeing a P3D Multiplayer SDK.
Currently, the accepted method of producing a dedicated MP Server, is to supply FS8/FS9FSX/P3D/Xplane players with a 3rd Party client application, like Squawkbox, that will communicate with the 3rd Party's custom developed server, using the 3rd Party's server's Multiplayer design, and completely bypassing the FSX/P3D simulators Multiplayer system. Works fine for Vatsim, IVAO, PilotEdge and FsHost., etc.
At least with a 3rd party Client-server MP system, the 3rd Part yhas control over both the client & server software, and is not restricted to have to update their software, if the simulator's MP system is changed.
Seems to me to be the best solution