In December, the development team had about written off anything to advanced for DayZ being designed and overseen by me personally. But as their gambles with direction have paid off, they’ve become more excited. Influenced by games like SS13 have made they see the real potential of an underground construction instance.

Once they have things really stable and solid, like a really good experience, they we will start with base construction. So yes, this is something Dean Hall wants to see. Both underground in Cherno and some kind of base building. But we are talking Q4 2013 at best here (probably as an entirely new game mode) (source).