Almost all the team oriented players I've played with (approx 5-6 different fireteams) have left the game beacsue there is no difficult end game content that challenges them. This is all due to Destiny constantly moving towards casuals and solo players. Nothing is difficult because of catering to players who don't team with others. The solo attitude harms clans because people keep leaving the game and most that remain refuse to play with others. So maintaining a group of active raiders becomes much harder as more and team oriented players leave. I have lost many friends and people I played regularly with because of the constant dumbing down in Destiny. Not even raids are remotely challenging. I know OP said that team activities need to remain but if they make a raid that is match made friendly then it's not going to be any sort of challenge for an organised team. Meaning that only the raid really represents true PvE endgame and even that is already very easy so what is there for teams to test themselves against?