I just read PC Gamer's preview of Original Sin. In that review there is a comment which would imply that this "RPG to dwarf them all" will PC / MAC only. Now dare I say this for fear of being accused of being too PC biased but in the preview there is a quote from Lar. This quote goes something along the lines of "Divinity 2 was not the game we originally intened it to be as we had to make so many compromises getting it to work on this stupid machine" whilst pointing to an Xbox 360.
So this would suggest that if Larian really do want to make the RPG to dwarf them all and it is 3rd person 3D then it would be PC / MAC only or on next generation consoles. 2015 is a long time off but current console technology sounds like it isn't good enough for what Larian really want to do in their games.
The only way around the problem would be a cutdown version for consoles. I wonder if Larian could have any input on this.
Joram - I think Larian have at least got to the planning stage for this "Divinity3" as I mentioned before Dragon Commander was an experiment so I think that is a clue that they are at least thinking of making a sequel to DKS in a similar style.
But again, only time will tell or clues may be given on lar.net etc.
