20 years old, how much longer will I have a decent amount of hair?

[Kxb34]

Hi, this forum has been a great support since i discovered my hair loss when I was 17. I am now 20 and started finasteride about 7 months ago. I feel it has slightly thickened my hair/hairline and if not definitely maintained. Now I know i'm no where near as far into the hair loss process as some members of this forum but I am definitely experiencing significant MPB and bear in mind I am only 20. Attached are some photos of my crown wet and dry, temple under normal and harsher light and my hair styled with product and dried.

So my question is based on these pics and my age (20) how long can I expect to have hair that is not obviously balding?