From what I gathered on their update you nailed it with the limitations imposed by the last-gen consoles. I also got the impression that this solution is not the final solution. That they are still working on a more viable fix across the board, but wanted to get this out there now to ease some of our problems. From what I also understood when watching the Cosmodrome ride along, they also had to par down the worlds and add buffer zones for transition's between spots on the maps due to the same memory and processing restraints from last-gen consoles. That said, I don't see Destiny 2 being available on those older consoles, unfortunately for some of the player base.