So in summary, no, proper MP will not be added as the game's core design simply doesn't allow it to happen.
this is only not possible if you want MP with many many players. MP with 2, maybe 3 players only would work. you'd have one user as the host user who generates the planet and acts like a server, and the other players then get the information from that player. you could have distance restrictions to reduce power requirements.
this would work similar to how Skyrim MP should be done.
People on here need to remember there is absolutely no MP in this game. it's a single player game. the only multiplayer part to it, if it can be called multiplayer, is the name of animals and such on a planet. if you do come across a planet another player has found and named, it will have some rubbish name and mean nothing other than a human some where once was some where on this planet too.
the number of planets in this game is used too much as a plus point. i've never heard anyone mention this for games like minecraft, but there are 18,446,744,073,709,551,616 possible worlds in minecraft, all proceduraly generated.
one thing that i would like to see in NMS if it's not in the game at release, perhaps added later, is mother ship expansion with crew that require management and the ability to walk around your mother ship. this would give something major to do in the game.
i assume the planets in NMS are going to be for the most part completely empty of civilisation. We're not expecting to find cities for instance, but empty planets with a little bit of life here and there.
... something must be wrong