They could. But they won't. And that's a shame. Because there is so much lore that's never really existed outside of text on a page. The game is in a terrible state but it is what Sony said, lightning in a bottle. There really is nothing quite like it.
I wrote a fanfic on how to end the franchise, showed it to a couple of guys I played with and they really liked it.
Destiny established the world. Destiny 2, eventually, ended the Light and Dark saga with a good expansion in Final Shape.
Where to from here ??
Well, how about stopping the collapse in the first place ??, we know how the Witness came about. Let's go back and stop that.
We go back and witness the collapse using Vex time tech. Imagine actually seeing the Traveller arrive and witnessing the upheaval and changes it brings. Then we work out how to go back and stop the collapse in another timeline. We know about Siva, let's use that and maybe even Rasputin. We get to witness historic events that we have only heard about. Like witnessing Eris losing her fire team. The backstory of Cayde in real time. I would love to see Savathun, Oryx, and Mara Sov back in the day. How about witnessing the The Vanguard Dare Cayde lost. Best bit ?? .. This is all lore that is in the game. These stories are long established. It's just bringing it back to life. Along the way a backstory comes about that our Guardians played important roles pre collapse, this gives our characters real meaning. Say your Warlock was a colleague of Ikora back in the sixties. You would end the game going back to that. With the knowledge of what she once was.
Could be great.
Making sure that the collapse never happens brings it all full circle.The new saga clearly isn't working. Not sure where else they could go.
Just a thought.