Yes a professional movie can be made only using phonecams. And the moviemaker is right in believing:
“I thought cinema in South Africa wasn’t the appropriate medium to represent who we are…it’s a mostly white phenomenon. Then it struck me that a medium that Africans love more than any other is the cell phone,” he told Reuters.
Clearly this is true for most of the world in addition to Africa. Given rapidly improving quality, things are likely to take off very fast in use of phonecams for different things — movie making is just one of those.