Originally Posted by
Goggindowner
Only minor villains have been killed off, really. Stane, Killian, Ronan, Malecath......who else? Loki is still very active, Abomination was captured, Red Skull was lost to time and space but wasn't killed, Thanos is still kicking, Ultron is likely to survive in some fashion (how do you kill something than can move its programming to a new host?), Winter Soldier walked away, Hydra effectively beat SHIELD, Arnim Zola could very easily have survived.
Seems to me the MCU is actually rife with potential villain returns.