I think the first season went very well so far. For me it was a lot of fun to play competitive dominion in this format and i enjoyed it a lot. And its my impression, that almost all other players enjoyed it a lot as well, it simply is a well thought-out and well executed format.
Its hard to set up strict rules regarding promotion and demotion, if not all matches get played. The situations of the groups will be very different, so will be the reasons for not finishing. I think, it would be best to set up some "soft rules" like Stef did with the guidelines in the Rules&Regulations-Thread.
I suggest to remove all players, who only played 2 games or less (<40 % or <50% of the games is also reasonable) . To be fair regarding de-/promotion, the results of the matches played by those players should be removed as well. It will be often the case, that Player X was able to play a match against the removed player, while player Y wasn`t, although he tried to contact him.
I would also ban these removed players for one season from league. As the active players shouldnt suffer from the inactive ones, the removed player should count as a demoted player. So in Division C1 where already one player has been removed (5 player division now), only #5 in the final standings should demote.
Edit: If two active players dont manage to play their match, the standings shouldnt be affected by that. For example if MX and Markowkette (sry to both for using you in my example
) in B2 wouldnt manage to play their last match in time, they just dont get any points out of their match and have to live with 0 points. 5 weeks is just a long enough period to play the match for active players. The current standings would be the final one in this example and yed should promote with 17.5 points.