The trick, of course, is to separate learning from assessment. The question was raised, why do you need to assess students? There are several answers to that, ranging from the simplest - I have to return a mark for continuous assessment to the School - through more complex - to provide feedback to students on their understanding - to heavyweight pedagogical navel-gazing (which I'll spare you for now).
I already have sets of online MCQs which the students on this module are allowed to use formatively, although only a minority do (and of course not the students who really need to). In future years, these will be used for periodic summative assessments, which will also provide feedback and a CA mark for the School.
The old discussion board (which was never used for any real discussion) will be replaced with a non-assessed course blog, which will have a supportive but mainly an educational role where I'll post questions and try to stimulate discussion. (It may be that circumstances force me to devote a small proportion of the continuous assessment marks to this activity. In that case, the problem lies in defining the rationale for the activity and concise and clear marking criteria.) I already know that only a minority of students will participate in this non-assessed activity. (I could even tell you who they are). So what about the rest of them? They are adults with a minimum of three years higher education under their belts. This is their final opportunity to grow up and take more ownership of their own learning. It's a jungle out there.