I really feel that the possession receiver gap is the biggest concern...
This. I'm not so worried about losing LaVon (yes, I realize that he is our statistically greatest WR ever) as I am about losing Riley. The dude had some just clutch catches this year, and very few drops stick out in my mind. When we needed a first down, we found Riley, and the sticks moved.
We had some success with using the TEs this year on 3rd down and near the goal line. We've got so many good TEs on the roster, too, that I could see us going more in that direction in possession passing situations. Roback could be the new Dunlop.