I think the important point about online relationships is that honesty is even more important than in person. You have to know that you trust the other person both to retain confidences that you give them and to do whatever it is that you ask them to do. If you have that, then there is little difference mentally and emotionally between a R/T and O/L relationship. The only difference is physical - you cannot actually touch the person you are in a relationship with. And even with advances in technology (webcams, remote vibrators, even virtual reality if it ever gets off the ground) that barrier will never be broken because even a remote access device is still at least one step removed from physical, intimate contact.

There are many devices that can make an online relationship easier. For example there are a number of computer programs which can control a sub while they have no Master/Mistress or even control them while Master/Mistress is remote or simply away for a weekend on business/away for the day at work. The best of these I have found is Cybermistress (which is currently being modified to also work for female submissives) which has a wealth of features. You can also do searches on self bondage techniques and other ideas for online bondage.

To my mind, it is only ever going to be a stop gap or a temporary relief of desires which, as pointed out, never really go away. Better to abuse a willing sub on line with strict rules and safety and consent than to inflict it on an unwilling participant and get hit with a domestic abuse rap (or, at the very least, scare a vanilla partner with your 'strange ideas about sex'.)