I still think D3 or the IP will continue. With or without Bungie.
It's not a secret that Bungie's management sucks. Right now, they have Marathon. Before they even focus on a D3, which is a massive $$$ sink, they need to start bringing in money. If Sony can salvage the game, it can pay the bills. Business wise, Sony wants it to pay for itself instead of investing more money.
IMO Destiny needs a CoD type of game management. 3+ studios working on it and releasing major updates alternating years. Can't rely just on one mismanaged studio in Bungie. Maybe they' can be the 'main' guys moving forward but to support a game like this they need a lot of help. Activision did it for a bit with 2 other studios and it actually worked out pretty well. Call of Duty has 10+ studios working on it.
It all comes down to Sony and how they want to handle it. Right now, it's just my opinion.... They want to try and get Marathon to a point where it can pay for itself and also mitigate d3 costs. Is that possible? yes. Is it likely? Who knows at this point, but they're in a deep hole... . infusing Destiny type of PvE into Marathon- campaign, end game for casuals ( strikes/raids/dungeons) , more pve depth will go a long way in building a player base though imo. If Marathon fails, I still think the Destiny IP continues, with or without Bungie.
A FROMSoftware, Destiny prequel in the dark-age after the collapse... I'm there for it.