I think what we're running into is a fundamental design issue. They'd probably have to completely replace the current vault at its core and the problems that would cause may be game breaking. I'm not justifying it but I think that's why we haven't seen anything else on it. They've just hit a wall on the development side because of how the base game is setup. I think at this point, we're going to have to take the changes they've made with TTK and hope that they have plans for Destiny 2 that offer more space to grow.