Will children not take the easy path, while away the time, become lazy or complacent etc?

This can happen not just with a child in open learning, but in conventional schooling / college as well as with us adults at any point of our life. And this is where the family plays an important role, closely reviewing, reflecting and understanding the child, and guiding with options that would work for that child.
Also, in our experience, since in open learning the child takes up leadership and responsibility of himself or herself (no one to blame), the child is also able to see himself or herself through low, slow or ‘do nothing’ phases, and decide their dedication towards their own goals and aspirations when ready.