Frankly all they need to do is allow modding, if that is even possible at this point, as if players can mod the game in any meaningful way the lifespan of the game will increase and so will sales. To add modding now would probably be difficult and if it takes to long it might be to late for more people to buy the game because of it.
That would be a great idea. I could see pouring tons of hours to understanding the code to make a few tweaks here and there. The game is awesome as is and I can definitely see it as the type of free roam game players keep coming back to over and over.
Just wish the devs were a bit more involved in helping guide community feedback.