BingJack offered some exceptional ideas here
Bwuh...? That's so odd. I guess I was due.
While I'm on a roll then, I think that it's a bad idea for units to be "locked" in combat in general, for every unit to be able to counterattack, or every unit to be able to tie up other units. However, I do like the idea of being able to deliberately build tank like units capable of tying other units up through the trait system.
The problem is, the tactical grid map in this game is probably not sophisticated enough to really pull off advanced tactical calculations like flanking or movement based Attacks of Opportunity. All that kind of stuff has to be modeled through unit abilities. But lord knows, we need more exciting traits for the unit designer, and a reason to build different types of units.
Consider traits like these, that bestowed actual battle abilities, rather than passive bonuses, that you could use to build a tank, or someone capable of running down and stunning an archer. Standard cooldowns apply.
Requires Shield. Range, any adjacent square. Inflicts "Staggered" condition, duration 1 turn. Staggered Unit move speed drops to 1 square.
Requires Shield. Requires Shield Bash trait. Inflicts "Staggered" trait in all adjacent squares for 1 turn. Casting unit receives "Dizzy" condition:-10 to Accuracy for 1 round.
All Allied Units receive +100% dodge for 1 turn. Taunting unit receives -100% dodge for 3 turns. Better pack some armor. (This one requires the AI to actually notice things like dodge bonuses for best results. It would be effective when used against the player, though.)
Unit immediately regains that turn's movement points. Loses all dodge until next turn.
Unit gets one Counter attack per round upon successfully dodging a melee attack.
Requires Counter Attack I. Unit gets one free counter attack.
Requires Counter Attack II. Unit gets two free counter attacks per round.
Some of those or abilities like them would be powerful when used with teamwork, or combos. A pair of "Tanks" in the skinny part of the tac map would be a formidable barrier. Tac maps may actually need to be adjusted.
Just ideas. But I think we're much more likely to see traits and special abilities , than we are to see fundamental changes to the combat system now. I do expect weapon damages to be adjusted so squads attacking first aren't so overpowering in the early game.