How about a Raid where we defend the city's walls from waves of enemies? Harder each wave, we can lay down turrets/actually man the turrets/activate tower guns to help defend key positions. Bosses follow after every few waves. Rewards appear after every boss and get better the longer you win the battles. This. This can help keep Destiny strong for a long damn time if emplimented right. Any further suggestions can be left down below! Even if this doesn't become a Raid, a Survival Mode type would be amazing just as well! Keep fighting the good fight, Guardians.