just an idea i got from watching good martial arts movies that might spice up the action in future MK games. i dont think such an idea was mentioned yet so ill go ahead and say it. it would go something like this (i'll try to be as clear as crystal)
Say that the 2 players pressed the same attack button at the same time. doing so will cause one player blocking the attack, leaving the enemy open for an attack, BUT, when the player(1) who parryed the 1st attack fights back, time will slow down, giving the other player(2) a chance to parry the coming attack and input his own attack. the result is 2 players in a fight sequence where constant parrying and attacks are flying back and forth (just like in alot of martial art movies). as it continues, time speeds up from slow motion, making it harder to parry your opponents coming attacks. and finally, the longer this fight sequence lasts, the more damage the final blow would cause, so you really dont want lose during "Q.T.E" (quick timing event)

As for the combo breakers, the fighter shouldnt just punch his/her opponent away in a middle of a combo, but just like in the above idea, the attack is blocked and the attacker gets a knuckle sandwich. what do u think?