This game would be amazing in co-op multiplayer mode. There are so few sandbox survival games like this that lend themselves to roleplay. The only ones I can think of are Conan Exiles and ARK. This could really be a contender and plug a huge hole in the multi player roleplay market.
That already exist with online and controller co-op
Hi Incendito, as Bisketti mentions: there is already co-op multiplayer in the game:
Second option on the main menu. Let us know if you have any issues with it.