I would love to see the military uncertainty represented by the fog of war extend to encounters at the tactical level, once the tactical battles are implemented.
This could begin with uncertainty when choosing whether to flee or engage an enemy group as to the exact makeup of the enemy groups. Having units with particular abilities, such as scouts, in your group could reduce this uncertainty. Units good at hiding could have a lower chance of showing up on that initial engage or flee screen. It might also be interesting to have a unit ability that forces a player to engage rather than flee once the engagement screen has been triggered.
During the actual tactical combat, the tactical screen would also use fog of war, with visible area unique to a unit.
Because this system would make unpleasant surprises possible, particularly for those who leap without scouting, it should also be possible to retreat units from the tactical screen, perhaps by moving the unit to the last row, then giving it a percent chance to escape every turn that it attempts to do so, modified by its speed and the speed of the units it is trying to escape.