Coulson's death was a manipulation by Fury. As a result Coulson get promoted. He's no longer a field agent now he's training the next level of field agents. Remember SHIELD was decimated in Avengers (Project Pegasus), plus maybe some of the agents he train may become street level superheroes. His job as field agent can be handled by Jasper Sitwell. Coulson could also be the liason for SWORD who we know is coming.