They did say they will have new mechanics. I fully imagine stuff like a debuff that if you taunt one tank you can't retaunt him until the debuff is gone, or periodic knockbacks off the tanks or three sets of shields on the tanks. Maybe on T&Z there are periodic mini Drook adds that come up. Possible a third interrupt needed in the mine field or more turrets or the squares behind you turn red after you defuse the next bomb.
You know, easy stuff like that