I know this probably won't be answered till gamescom but I thought I'd see what people think. From reading Lar's posts I think this game is set decades after the events of DKS and you play as a new dragon knight. I might have got it hopelessley wrong but I think the main character will be the son or daughter of the DK from DKS and he / she aspires to be much powerful than his parents were. For example researching Maxos era technology and building the empire for his / her own personal goal.
I don't think it's set in the past as it could contradict the story of the games released so far. What do others think?