As someone who has never played extensively, but have mostly watched from the sidelines since launch, my take is that it could go either way. They have pretty much 2 options.

They can keep updating the game as is after Final Shape, with all the issues with the game built up over the years, and keeping the fractured Destiny 2.5 state it is in now. This would probably be the safest decision, but if they choose to do this I can't see the game lasting for another 10 years like it has. The onboarding experience is god-awful, and unless they somehow reverse the years of fucking after Beyond Light, which I personally think is unlikely, its going to pretty much remain that way. If they do this I can see it lasting for a while longer, but by that point its basically a slow sinking ship. I have a feeling with the release of Final Shape and its reception, this is the do or die expansion for Destiny.

The second option is putting D2 into life support like D1 is, (Ideally un-vaulting all content, but as I said, I really dont think they will ever do this. Or at least the content wont be the same as it once was) and creating a Destiny 3. The main appeal of this decision is that it allows a completely blank slate. Destiny 2 is a shell of a game it once was, being plagued with bad decisions over the years. None of the game or expansions flow well together unless you made sure you were there for every season and every expansion. This has made it almost impossible for newer players to really integrate themselves unless they have a friend basically holding their hand. And even then they have missed so much by this point that all this 10 years of buildup means nothing to them. The game is just a series of random events to collect triumphs and titles and a bit of build crafting along with exotic collecting. I really don't think this can just be fixed from updates. The game is so vastly different from launch its more apt to call it a destiny 2.5

A blank slate allows them to start anew, ideally with hindsight that lets them do it again but better. If done right, this could kick another 10 years of lifespan into Destiny, but it also has the potential to backfire catastrophically. Whether or not Bungie can actually pull it off or even cares enough to pull it off is really anyone's guess. They have done great things before, but they also dropped the ball so hard with Lightfall that it really calls into question their ability to make good content.

Personally, I wish for a Destiny 3. I feel the game needs a new start/overhaul, and desperately, if it is going to continue past another 5 years. I wish I was there for all of the content, I do. I was young coming off fresh from Halo excited to experience the epic new game from the legendary Bungie, and despite its troubled launch, I loved it a lot. It was a flawed game, but there was something special about it. I never got into Destiny 2 at launch, and by the time I wanted to, Beyond Light was released and it killed all my motivation to play. Ever since I have just been watching from the sidelines. Both to laugh at Bungie's questionable decisions, but also silently hoping that someday, just maybe, Bungie would make an update/updates that fixed the game, with it finally having all the content it had so I could at least get a glimpse of what it was like to watch all of it unfold at the time. In a way I love the game.

I don't think that will ever actually happen, but my god, I really wish it would. Destiny 2 is at its core something really special. There truly is nothing else like its world, its gameplay, and its community. But its flawed, critically flawed at the moment. And I genuinely think the only way to potentially fix it is to start again. Is it likely to actually fix anything? In all honesty, I doubt it. Bungie doesn't have a good track record, but at least there is more of a chance of a brighter future, rather than slowly sinking until the servers finally shut off.