My T has said "I'm not going anywhere" and then she'll sometimes qualify this with "that I know of" or kind of jokingly say that she could have a heart attack or something tomorrow, but then reassure me that she is in good health. I've needed this after people have left me and she knows that. It comforts me and I don't see anything wrong with it because she does say that something could happen to her that would be out of her control. I know that she is firmly rooted where we live - has lived there all her life, her husband is retired and he too has family there, and she is in her late 50s so not planning some sort of job change.

Maybe your T is trying to show you that you can have the experience of not being left to counter previous relationships that you've had in the past. And I can totally understand how this statement could make you uncomfortable (and maybe too that he said it early on in your work), but maybe you can see it as a gift that he keeps giving you? Also, it can be interpreted as saying "I believe in you," "I want to help you," etc.