What keeps them engaged with Destiny 2 despite its apparent lack of a clear path forward?

There is no alternative. The First Descendant is p2w. Once Human has different structure and resets your progress every season. Warframe is pretty different and similar to First Descendant. Overwatch basically cancelled its pve. Darktide is clunky.

And none of these games have the polish and shooting satisfaction that Destiny has. If people want a pve game, with long term progression that has enjoyable shooting, Destiny is all there is. What keeps them playing? Copium.

Slowly but steadily Destiny will die. And thats when Marathon will come out. But Marathon is very different, so i am not even so sure that most Destiny players will migrate to that.

I am not even playing Destiny. Destiny is the game that i want to love so much but always shits on me, so i gave up. It seems to me that the easiest thing in the world, is to keep Destiny going and address its minor issues. But somehow Bungie doesnt think so.