The Daily Mail is reporting that Chelsea have offered Thibaut Courtois a lengthy contract extension, but that the Belgian hasn't yet signed the deal due to some concerns about his future at the club. According to their report, Courtois has concerns about coming back to Stamford Bridge next season only to find himself buried on the Chelsea bench. The Mail go on to state that Courtois would be willing to return to fight for a place at Chelsea, as long as he's comfortable that current form is the determining factor as opposed to reputation.
It's hard to be too critical of Courtois for wanting to assure he'd get a fair shake, as he's good enough to start at all but a handful of clubs on the planet right now. He may well already be a better option than Cech, and he just seems to want assurances that he'd be given the chance to prove it.
Jose Mourinho has also shown a patience-testing amount of loyalty to certain veteran players in the squad, regardless of whether or not their current form warranted that regular place. In fairness to Mourinho though, not many of those underperforming veterans has a player the caliber of Courtois breathing down their neck.
There's also the case of Belgian teammates Romelu Lukaku and Kevin De Bruyne, both of whom have made headlines with their unhappiness recently. I'm sure seeing the pair struggle to get a look didn't help alleviate these concerns, especially as he's spent a trio of international breaks with the pair since the start of the kickoff of the 2013/14 season (as well as one just days prior to the season getting underway).
The good news for Thibaut is that Mourinho has shown a willingness to make a change in goal before, both at Chelsea when he went with a very young Petr Cech, and at Real Madrid where he benched a struggling Iker Casillas despite his stature at the club. In that regard, there's at least some history showing that Cech will need to perform in order to maintain a starting spot.
Personally, I hope the club do whatever it takes to assure the youngster that he'll be be given a fair shake next season. While there is still plenty of time left on his current contract, it would be in the club's best interest to see him extended as soon as possible. If that means Petr Cech has legitimate competition for a starting role next season, so be it.