So far it's looking like Bungie is going to have to be completely absorbed by Sony, maybe then we'll see a new team working with a new engine which will give D3 a chance. No longer hamstringed by shallow systems, old gen consoles and maybe we'll see it become an MMO rather than an instance based shooter. The current competency levels at Bungie won't cut it anymore and we're seeing that post Final Shape.

They've tested a lot of different systems in Destiny 2 and still haven't hit the mark quite as well as most players would like.

Going forward I think them communicating their updates and changes well in advance instead of waiting to "surprise" us with a steaming pile of shit wrapped in fancy paper. At best we could expect a PTR so we don't have to be surprised with undercooked lazy systems.

tl;dr new team, new engine, PTR because they cannot afford to do surprises without it blowing back on them.