I m sorry to say this, but the actual reason why the ban is in place and adhered to, and the reason why Dorje Shugden practitioners are regarded as demon worshippers. and the mainstream of the Gelugpa tradition is regarded as a 'sectarian wing' and sidelined, is the Dalai Lama's credibility. Most Buddhists simply believe what he says because he is respected as an authority figure. To most non-Buddhists he is the 'pope' of Buddhism.
The problem, therefore, is two fold - what the Dalai Lama says and how he is regarded by the vast majority of people - including mostly the people who post on this website I expect!
I don't believe that people will pay attention to complex arguments regarding the validity of Dorje Shugden practice, they simply follow the power of the Dalai Lama's speech therefore, sadly, the way to solve the problem is to undermine his credibility as an authority on Buddhism by highlighting his hypocrisy. Even so, there is an enormous barrier to be overcome here too because most people simply refuse to believe anything negative about him. Detractors are labelled as deluded or Chinese agents (a convenient way of distracting people from the main issue of sectarianism and ostracism).
I don't know that the WSS will do, but my own feeling is that as I have said, the Dalai Lama is the sole source of this problem and the solution lies in highlighting his hypocrisy and the injustice of the ban, in contradiction to his words about peace and inclusivity. I have no hatred for the Dalai Lama. I did at one time, but now I that I see his legacy is one of destruction and failure, I feel sorry for him. I feel glad that he has been a conduit for many people to find the Dharma but this doesn't begin the counterbalance the massive destruction that his actions have caused and continue to cause, and will likely cause, for many generations. People here talk about lifting the ban but that will never happen because there is no reason for the DL to do so. Action needs to be taken to protect our spiritual lineage for future generations and, notwithstanding the great contribution of the people who operate this website, it will not be enough for as long as the Dalai Lama's credibility is stronger than this website's voice. People need to receive information about the truth of the Dalai Lama's actions.