If they decide to go down a dark route for her exit storyline how dark could /should they go ?. Clara lost Danny last year which was sad but so far Clara herself has escaped any permanent physical or psychological damage. 
If the doctor finally says or does something to destroy their friendship that's one thing.
Sustaining a life changing injury is another. Could be terribly burnt and scared she does have such a pretty face after all. Paralysis is another stuck in a wheelchair for the rest of her life. Companion who can't run from a threat is not safe.
Clara could even have a similar tragedy to Amy. Undergoing a emergency hysterectomy before she even has a chance to experience a pregnancy and birth.
She mentioned wanting children so not impossible she could walk away because every time she looks at the doctor she is reminded of her loss.
Would prefer a happy ending but could prepare for more heartbreak for the Doctor and Clara if her time and luck finally does run out.

If the doctor finally says or does something to destroy their friendship that's one thing.
Sustaining a life changing injury is another. Could be terribly burnt and scared she does have such a pretty face after all. Paralysis is another stuck in a wheelchair for the rest of her life. Companion who can't run from a threat is not safe.

Clara could even have a similar tragedy to Amy. Undergoing a emergency hysterectomy before she even has a chance to experience a pregnancy and birth.
She mentioned wanting children so not impossible she could walk away because every time she looks at the doctor she is reminded of her loss.
Would prefer a happy ending but could prepare for more heartbreak for the Doctor and Clara if her time and luck finally does run out.




