i think this is one of those typical difficulties when highly talented players go on a loan to a strong club like Real Madrid. When they play an amazing season and Kepa performs in a considerably strong way for the season, what are the chances that Chelsea would not want him back especially when Real Madrid even wins titles with him? If they let him go, then it will be very expensive, but at the same time they will have Courtois as well.
But it could be an interesting transfer for Real Madrid because Kepa is three years younger than Courtois. He is not quite a new generation, but three years is still worth considering when Real Madrid thinks about the future on the goalkeeper position. Courtois' injury isn't a light one, it is a severe condition and it takes time to see whether his knee will fully recover.
If Kepa succeeds with Real Madrid in getting the title for this season it will be an advantage for Chelsea because Kepa is only on loan for one season by Real Madrid and when the loan contract runs out and Real Madrid wants to add an extension for Kepa indirectly Chelsea can easily ask for even higher prices.
Courtois had an injury that took a long time to heal so it is a good opportunity for Kepa that he is a talented goalkeeper and by playing for Real Madrid Kepa can also make his career grow.
Although Kepa is one of the good goalkeepers but in reality, at Real Madrid Kepa is only a player who is on the bench. Thus, Kepa is not the first choice at Real Madrid and that way, at least provides evidence that the quality of Kepa at Real Madrid is only limited to second-tier players. Also, in this contract or loan there is also no extension option and also no permanent transfer option. Thus, Kepa will only be at Real Madrid only this season and no more.
Kepa just joined Real Madrid not long ago and when Kepa can show what he is capable of then it is very likely that he will be made the main goalkeeper.
It's still quite early for Kepa to come first and he needs a few games to prove all that.