i don't see any room for the player that will be forced to leave , the 5 people we would have to kick won't go to any random getto if they keep playing.
and every kd that puts time in to the game will have 20 players , so the 5 that is forced to leave are force to play in getto's sence they can't join up with 15 other people
that got force kicked and build a kd.
So all this is doing is forcing 5%? to quit the game more or less, sence most of the kd's with 20+ players got active players that want to play with other active players.
This is like the "dice takes pool" suggestion , it will just get the top kd's in range to feed on gettos and mid tier kd's.
If you want someone new to war , just grow some at the start of the age , and you will have 10 new kd's to war.