Multiplayer development will now start.
There will be some small updates for other fixes and improvements while multiplayer is being worked on, but most effort now will go towards getting multiplayer ready for release.
See here for a modded multiplayer solution in the interim. This mod provides a replacement for the Xbox Live servers and leverages the games existing multiplayer code for Xbox. Note all new PC features are not yet supported, and some features which I've changed during the PC port also will not work properly. But basic multiplayer hosting and building is possible.