The reason I write this is because, now that Coulson is leading Shield, he should be reintroduced to the MCU films, and here is why.
Coulson is the reason the Avengers became the team we know them as today. Without his death in the first film, we may have not have seen them unite. Now that they're torn apart in "Civil War", he could be the force that once again brings them back together as the team we all love, and to fight the villain Baron Zemo. Also, Coulson might reappear to defend gifted individuals. But, seeing him in Civil War would, in my lowly mortal opinion, be the best choice . The Avengers think he is dead; killed by the villain and adopted bother of Thor: Loki. Him returning would really hit them emotionally.
Again, with the amount of Inhumans and gifted people showing up, someone will have to explain to the government that they are not all out to kill you, and destroy life as we know it; to stay calm and level headed is the best option. We all know the government fears people with powers and anything they can't understand or control. These are just a few reasons I think the lovable and extremely awesome Coulson should return.
Thanks for reading:)