Wonder if Clara will find herself in a similar situation to Amy and Rory in S9. Like her they knew and travelled with the doctor for a long time. They also tried to balance trips through time and space with a "normal" life. Family, jobs bills ect. End of POT they chose to carry on traveling with their "son in law" .Brian even gave them and 11 his blessing. Told them to save as many worlds as they could. Next the angels got them in New York. Clara nearly gave up the Tardis in MOTOE Doctor even described the traveling as an addiction. Said you don't know if you can give it up until you stop or something like that. We saw Clara all be it briefly as a old lady in LC. However that does not mean she will actually make old bones. Sweet how he didn't notice still saw her as young and pretty. Traveling in the tardis is dangerous doctors enemies become you enemies. Clara and the doctor might just run out of luck and time in S9 bringing the story of their friendship to its end. Question is what would she sacrifice to keep traveling with him ?.

For some reason, I don't feel like Clara has been with the Doctor for long, despite her almost overtaking Amy in the episode count.

This is why I'd have liked Clara to actually have stepped aside in the Christmas special as I feel too often do companions get forced down the road of a traumatic exit particularly when in Clara's case (just like Amy/Rory) she's out grown the adventures. We know she won't still be travelling the universe into her 80's so it seems like her time is up even if it feels as though she hasn't been around long.