He will care about you as long as you are useful to him - that is the depth of the care he is capable of if he is a narc. Don't lose your looks whatever you do, that will likely be what you are valued for - if not then you are merely the security blanket that makes him look like a good husband and father while he shags around elsewhere.
Narcs are deeply insecure - they will say anything to keep you, you are a toy or pet to be owned to them, people are just pawns that are useful or not at which point they are easily discarded. Narcs have no true self esteem, they need to be constantly reassured and told they're great, while at the same time they have huge egos and think they are too good for anyone. They want perfection in the person they are with, model face, porn star body, impressive job, that's what they think they deserve and if they don't get it then it's not down to them it's down to not being properly appreciated and they become very bitter. No matter how perfect you start out though and how much of a pedestal they put you, on over time you will show imperfections and eventually you'll fall off and be found wanting. He will never be wrong about anything, it will always be someone or something else's fault, you might be the scapegoat, or your kids but it will never be his fault.
He will say things so absurd you will think he must be joking, he won't be - but he'll be the king of back tracking/forgetting he said it/telling you it was a joke. He will lie like a psychopath and gas light you to the end of your days and he will be obsessed with looking good but have no care for being good. As you can see after 25 years of experience I can safely say that narcs are bad news.