Hi
Look on my some ideas.
Game theHunter: Call of the Wild™ have some good DLC, need some here(example: tents, atv).
More elements to solo play.
Normal swimming with animation.
Pontoon to fast travel on water.
Better night and morning(more night sounds, turn off/on lights in bicycle, binocular with night vision, morning dew, ect.).
Less empty world.
Meet wild animals.