Online D/s is perhaps one of the most controversial subjects in the Dominance and submission community.
The stance I will take on this subject, based on online D/s relationships of My own, is that YES; it can and does work. Is it anything like real-time, face-to-face Dominance, and submission relationships? NO, not at all.
That said, it is still very real and intense for those of us in online or Long Distance Relationships (LDR), and often can and will lead to a real-time (RT) relationship.
In My opinion, the most important thing to remember here is safety.