The 21-year-old goalkeeper has enhanced his profile considerably during three seasons on loan at Atletico Madrid.
He is, however, contracted to Chelsea and is considered to be the long-term number one at Stamford Bridge.
Blues boss Jose Mourinho sees things that way and has already spoken of his intention to bring Courtois into his plans next season.
Petr Cech will still be very much part of the fold then, though, meaning there will be two ambitious internationals competing for one spot.
Courtois is unwilling to take a step backwards after enjoying such a productive run in Spain and has made it clear to Chelsea that he will expect to play regularly if he is kept in England.
His father Thierry said in The Sun: "Jose Mourinho has told Thibaut that he's expecting him back in the summer.
"Petr Cech is in place at the moment. On paper you could alternate the two of them, but it's not the type of situation we are looking for.
"With the level Thibaut is at now, there is no way he will go to a club and be second choice."