Even with the delay, it's not that long until Shadowkeep, the next Destiny 2 expansion and the first one to go live on Steam/the Activision departure. But if you haven't installed Destiny 2 prior to that, then I hope you've cleared some space.
Destiny 2 is already on the larger side of life as far as games go, which makes sense: it's a huge games-as-a-service title, one of the more graphically intensive on consoles particularly with multiple expansions. That's a lot of content that takes up space on your hard drive.
So the fact that Destiny 2 already needs just shy of 100GB (and slightly under 90GB on PC and Xbox One) isn't that surprising. There's the bit where PS4 users need way more storage space than that just to install the game, but again, this isn't hugely beyond the pale.
Interestingly, the official Steam page right now says users need a "minimum" 105GB hard drive storage space on PC. But that's nothing compared to what PS4 users will need after October 1, when Shadowkeep drops:
That's almost a third of a stock PS4's hard drive, and just over 15 percent of a PS4 Pro's stock 1TB drive gone in a single game. I mean, holy shit. That's a hell of a lot for the install size, and while the full download — particularly anyone on PC who's only picking up the game when it drops on Steam — won't be that much ... it's still a hell of a lot.
If you don't have NBN or decent cable? My condolences.
There's no word on whether Xbox One and PC users will need a similarly enormous amount of hard-drive space from the off. It's also unknown if users downloading Shadowkeep for the first time will also have to download content from the free-to-play Destiny 2 version that's launching around the same time. Bungie usually provide more detail in the weeks leading up to content patches. Fingers crossed there's some compression wizardry they can squeeze in before launch, too.