There can only be so many simultaneous events. It's a side effect of the anniversary tournaments. Not only do they benefit only to people who are prepared to sacrify tons of units (and buy them back, of course), but it penalises standard players who have come to count on these quests to obtain boosts and other rewards.
I guess 'some time' is exactly 2 days and 23 hours from now, when the 2 coiner tournaments are over and the limit of 3 or more tournaments is no longer reached...
Coalition Missions are cool and provoke activity as well as bring in the element of small but regular rewards for the players. Either way, looking forward to having these back in the game!
Thanks!