Yes Cech is not as good as he was before, but he is still a good GK and a rather reliable one which is something really important for our shaky defense. Courtois is still young and there is not need to interrupt his loan at Atletico when it's going so well. Let the lad grow there and brake a few more records De Gea was good at Atletico also, but he is struggling now at United due to pressure and physicality of the league. For me, the best possible scenario is to keep Cech for a couple of more years then bring back Courtois while Petr is still here and have them together for a season and see with Petr is he's comfortable as being a 2nd choice GK. He has made a couple of mistakes this season and wasn't as good as last season, but he still made some great saves and saved us points.