It is possible that the new content will include a new or expanded open world map. I hope this turns out to be true, and that we get a bit more variety, and less predictability:
Invaded Control Points
Have control points in invaded sectors taken over by Black Tusk. Have the attacking wave be dropped off by helicopters. Some people have argued that this wouldn't fit the lore, but the lore went out the window with Summit and Faye Lau's death IMO.
Black Tusk ambushes
These were added to the DZ awhile ago, and would fit just as well in the invaded sectors of the LZ. For those who don't go in the DZ, Black Tusk helicopters will randomly drop off elite enemies on top of you in the open world. Maybe drop legendary enemies on heroic world difficulty for those who like to spice things up.
Multi-part activities
Introduce roaming multi-part activities akin to the old "Search and Destroy" missions from Div 1. The roaming aspect will help with making the world feel more organic, and the unpredictability of activity types will keep them feeling fresh for much longer. For example, defending a friendly supply convoy might reveal the location of a hostile supply dump. Clearing that out might reveal the location of a bounty, or trigger a black tusk ambush.
Additional Bounty locations
A lot of effort was spent on the side missions, and many of those locations are re-used for bounties. However, quite a few are not - e.g. the police station roof in WoNY. There are also a few locations which have never been used for anything (e.g. various office interiors in WoNY, a bar in DC).