Will thick hair last forever?

Both my husband and I have very dark, thick, and healthy hair that is the epitome of fullness.

But lately, both of us have been losing a lot of hair.

Fortunately, my hair is still thick, perhaps because it grows back as much as it has fallen out.

But lately, I've been worried about how long this thickness will last.

I wonder how I will cope with the sense of loss when I reach the age where I can no longer grow back as much as I have lost.

My husband has been managing his hair roots with anti-hair loss shampoo for a long time, so I think I should switch shampoos and take better care of my scalp too.