David DeGea has been a great servant for the club, but all the signs are he is beginning to wane and his weaknesses (crosses under the bar/playing out from the back) are now likely to be more important under ETH.
Henderson is still learning and could get better, I'd keep him, play him and have DeGea as stand-in.
ETH has to change things and where obvious weaknesses with any player that have existed for years, and not improved, then they have to be addressed now and not just with outfield players.