I'm getting the idea that Gurdjieff was talking about a combo mastermind / community of practice.
Mastermind "There is synergy of energy, commitment, and excitement that participants bring to a Mastermind Group. The beauty of Mastermind Groups is that participants raise the bar by challenging each other to create and implement goals, brainstorm ideas, and support each other with total honesty, respect and compassion. Mastermind participants act as catalysts for growth, devil’s advocates and supportive colleagues"
Community of Practice: "A community of practice (CoP) is, according to cognitive anthropologists Jean Lave and Etienne Wenger, a group of people who share an interest, a craft, and/or a profession. The group can evolve naturally because of the members' common interest in a particular domain or area, or it can be created specifically with the goal of gaining knowledge related to their field. It is through the process of sharing information and experiences with the group that the members learn from each other, and have an opportunity to develop themselves personally and professionally (Lave & Wenger 1991). CoPs can exist online, such as within discussion boards and newsgroups, or in real life, such as in a lunch room at work, in a field setting, on a factory floor, or elsewhere in the environment."
Back to the original post:
"Unlike Influence B, Influence C cannot be taught, but must be experienced directly. The experience can be shared with others, but only those who have themselves experienced that particular Influence will understand it. A fair example is the feeling that a parent gets holding their child on the day he or she is born. "
There's a name for this in NLP. It's called a reference experience.
"Do we have those among us who are capable of picking up that Third Line of Effort; effort for the cause?"
Been there, done that. Miss the synergy of the CoP, not the 'cause', unless of course the cause is the advancement of a discipline, technology, etc or could be classified as increasing 'human potential.'
"Can that Third Line of effort be truly engaged through virtual reality?'
Yes. Easily and successfully with people who have the mindset.
"Finally, if the answer is "yes" to both questions, what would that cause, that common task, be?'
Like your article says, it can be anything. I've found CoP's are best when noobs are learning the basics from the veterans, but the veterans are pushing a technology/art/discipline and themselves into entirely new territory.
I found this in a book recently, it expresses how much I miss this sort of thing :
" Learning organizations are possible because not only is it our nature to learn but we love to learn. Most of us at one time or another have been part of a great "team," a group of people who functioned together in an extraordinary way, who trusted one another, who complemented each others' strengths and compensated for each others' limitations, who had common goals that were larger than individual goals, and who produced extraordinary results. I have met many people who have experienced this sort of profound teamwork. in sports, or in the performing arts, or in business. Many say that they have spent much of their life looking for that experience again. "
All the above is what came to mind while reading your post. Please respect my divine non-authority.