This really depends on the definition of ‘successful’. If I have joined a MOOC and learn from it but due to time pressures don’t finish the course I don’t consider that a failure. However, with regards my MSc online if I don’t pass the course I will consider that a failure as I wouldn’t have achieved a formal qualification and lost money. Yet, the learning is still judged on the learning not whether it is online or offline.
Flipping this if I passed an online course with the absolute minimum level of engagement with fellow students and teachers then I personally would consider this to be unsuccessful as an overall experience. This is because I value the ‘hidden curriculum’ learning (discussions, shared learning, new technology skills etc) as much as the assessed elements but this may not be the case for everyone.