Hi Kai,

It isnt possible at present - you might be able to rig something up using grades, but it wouldnt be fully automated. 

I think having this kind of logical course completion criteria is a good idea though, I've created a Feature request, TL-10900, and posted in the Suggest Features Forum for visibility and comment. We'll let you know the outcome of our review process in due course.

cheers,

George.