I think cartography would be something I could get into.
I don't think anyone could make a living making maps anymore. Would this just be a hobby?
Yeah I have enjoyed making maps for games like Dungeons & Dragons in the past.
People have been making maps since  4th millennium BCE. I'm also not sure anything exist that still needs mapped.
Yeah the old maps that show how we developed are interesting to .
I have one on my wall from 1244 Scotland. It has been in my family all those years. I love maps of the ancient world  like the Minoan Map "House of the Admiral" wall painting from c. 1600 BCE, showing a seaside community.
I have never seen that before I will have to look it up sometime. 
Early maps pose a lot of debate because the term Map isn't well-defined some artifacts exist that may or may not be maps. 
Interesting I wonder how much information has yet to discovered in some maps.
Some say the he Age of Discovery, or the Age of Exploration was from the 15th-18th century but I think it's no.  With the help of technology we can discover so much.