Hi, I have some suggestions regarding player reliability, skipping and quitting.
There are many games, where players, sometimes even the host, are inactive or in permanent vacation mode and therefore are more an AI than a real player. In my opinion this is not what GMR games should be like. The ideal game for me would be a game where everyone stays and plays from the beginning until the end. For games like this to happen, you have to know whom you can trust and who is more likely to leave sooner or later.
Right now we can roughly tell how many games a player played through his GMR points. But sometimes more points do not necessarily mean that a player won't quit a game. Therefore I suggest implementing kind of a rating system into the new GMR.
Every player has a rating ranging from "Inactive", "Untrustworthy", "Casual", "Trustworthy" to "Very reliable" (or similar).
When creating a game one can choose a minimum rating a player must have to join the game.If a player drops below the minimum rating of a game the host has the option to kick this player.
Of course behind the rating system there is some math. How it is implemented into GMR is up to the developers, but I thought I'd give some suggestions. First I would bring in a point range from 0 to 100 representing the rating. Your rating is the sum of your positive and negative points:
Positive points:

• Played turns/Number of Games * 1
  
• Finished Games * 10
  
• Player rating * 1

Negative points:

• Skipped turns/Number of Games * -5
  
• Quitted Games * -20
  
• Player rating * -1
  
• Inactivity (<1 played turn per week and not in vacation) * -1

However, as you can see for this system, we would need some kind of ending a game. This could perhaps be done by a vote where everyone agrees that the game is over.
Another addition is the player rating. What I mean by that is, that every player can give another player a rating like +1, -1 or 0 once. It is kind of like your opinion about how someone else should be rated. You should be able to change your rating for another player whenever you want.
Note that the system I just explained is completely made up and I have no idea if it would actually work. But I do think that the rating systen as a whole is a good idea to improve our overall gameplay experience in GMR with less AI's and more players.