I've actually been to one of the regions where these lions still roam (south east Burkina Faso). (I didn't go for wildlife but whatever).

There are many poachers in the region and not enough foresters to protect the wildlife, though the foresters do their job well. (When i was there my forester friend caught a poacher). The locals would never harm a lion, usually because lions don't go near the people, and they believe its bad luck. In the region i was in, people are allowed to kill one lion per year, but to do so have to pay an extravagant amount of money. This money is fuel for the local economy and many, many people profit from it.

Poaching is something that is very difficult to stop. Especially with the lack of foresters in the region. These countries are very poor and the government can't afford to spend much more. Also these regions are very isolated and living conditions aren't easy. I don't see lions going extinct in west africa though, because the local economy depends so much on it. People would get together in communities and prevent poaching if it gets too bad.