so ya think the game is set to where they dont want multiplayer? or is it possible? It could be a hit or miss for the developers!
There is entire market for Multiplayer RPGs you there. Why compete with them if you have your own market where your game shines?
Multiplayer as afterthought or just planned DLC would require a lot of coding, mostly to game engine itself like da mage said. This would
take a lot of time and work effort. And it could even cripple the engine and just create load of new bugs and issues for those playing singleplayer as well.