I will say, had ANYBODY else been in charge of the Anthem team I believe it would have found success the same way D1 did after a while. D1 stumbled a bit out of the gates too, so not sure why companies think that a new dev can make something in the same genre with no experience. Had EA not been so obsessed with the microtransaction crap, the gameplay was very good, visuals were stunning, really all they didn't have was an end game (Which Destiny still offers very little of even to this date). I hate that Anthem 2.0 got canned.
The thing about Bungie and this game that bug me, is that they have some of the most fun gunplay in a console shooter, but they continue to push D2 into Ability Simulation the game, and if I wanted that...I'd play Overwatch and have more fun. They still have this big problem with not knowing what they want this game to be, outside of a dying cash cow that they'll keep beating til it's toast. There isn't a solid vision of this is what we want the game to be, they just kind of go from one weird idea to the next while putting band aids everywhere they can while saying they are listening and working on stuff.
As far as Activision? I think if they could build a team with some of the great people Bungie has for some dumb reason let go along the way and folks who can actually meet deadlines could easily bring something to the market that pushes this game and could possibly finally knock it into the ground, but modern gamers are...? Awful? All they want is Battle Royale games with basically loot boxes disguised as costumes so there aren't teams out there wanting to create something like this outside of Borderlands which you said, and I can easily say I have had more fun in BL3 (Even with a shit story) then alot of my time in Destiny. Maybe could be that they focus on releasing more then 6 new guns a season, and lean into being a shooter better then Bungie.
I'd be super interested to see Gearbox put together a team to make something closer to Destiny as a new IP for them, but with the focus on Guns and Gameplay over alot of what Bungie is currently worrying about.