There is only one way they can guarantee a purchase from me and many others at this point:
True offline mode
Changes to game play to fully accommodate the single player mode
At this point, simply allowing offline play and local city saves will not fix this game - the game play punishes you for playing alone and needs serious redesign to be complete. For instance, time frozen regions.
If they can accomplish that and of course make it a free patch, I will buy it.