@OP there's no such thing as a "mature hairline." It's hair loss (male pattern baldness). A mature hairline is basically just a NW2 which has stabilized. Will it stay stabilized? Who knows! Does it matter whether it's "balding" or "mature hairline"? It's just semantics.
Only two things matter:
1) Will it get worse? (No one knows, but you're getting to the age where does it even matter? You have a fantastic head of hair for your age and you can easily hide your temple recession if you care to. Or just rock it, because as you get older a NW2 looks better and better imo)
2) Do you want to do anything about it?
Personally I'd live my life if I were you. I'm also a """mature hairline""" haver except I'm 31 and a lot of haircuts for people my age just don't work for me. If I were 44 with my hair I'd be overjoyed.