Odds of Hanging On
Odds are good if you don't get shot. Actually, the economy's slow-down has harmed taxi drivers. Less people travel, which means there are less people in tourist areas. However, people will almost always need taxis in urban areas, so as long as you can maintain under pressure there is a good chance you can hang in there.
Taxi driving has a high turn-around rate. Not very many people are career taxi drivers. The more experience you have, the easier it will be to pave a way for yourself in this career. Or to pave a way in a career that doesn't involve looking at so much pavement.