This is not something anyone knows the answer too, let alone a bunch of strangers of a forum who have no knowledge of their medical history.
I think this is a question best asked with her nephrologist, who has all the relevant information and knowledge.
Some people can keep this up for a very long time, others get unlucky and catch a virus or such, sending them into quick deterioration.
I wish them all the best and I hope for a successful kidney transplant soon!
As @Antje77 said this is not a place where people will be able to provide you with any advice in relation to the question you're asking. I recommend that you speak to the medical team responsible for the person.