I would think that one of the biggest challenges of distance learning is the costs involved. The provider needs to set up the system (technologically) so that students can access it, hire the teachers, establish curriculum, provide necessary materials, and then support the system. In this age of technology, we know there are always technical difficulties that occur. The provider needs to have a system in place that will prevent/fix these that minimizes student frustration. Also, on the student side, there needs to be access to the technology. Some students who cannot afford regular college may try to take some distance learning courses. However, ...
This answer describes some of the issues and benefits of distance learning.