Villains
One of the major complaints the MCU gets is the lack of a strong villain beside Loki. In fact, Thanos could be the solution to that problem but that is a long wait to a good villain. The villains undeveloped and stereotypical mustache- twirling- bad guys. The MCU could solve this but there is this juggling act of managing an increasing number of heroes and giving the villain actual depth. The heroes are more important and they consume more screen time; so expect more weak villains.