It is not possible to create a DLC that will fix this game. This is not possible for quiet, economic and many other reasons.
To fix this game, they just need to remove this game from all computers in the world, erase the memory of the players about this terrible disaster and release a COMPLETELY DIFFERENT GAME!
The very game they promised in the trailers. With a non-linear plot, many ways of passing missions, choices in dialogues that affect at least something.
If they bring the subway back into the game, it won't change anything.
Returning the run on the walls will not change anything either.
If they add police chases, it won't change anything either.
They can fix the balance, make throwing knives more useful and interesting. But even that won't change anything!
Because the problem is at the core of the game's entire game design. This whole game needs to be redone! And no DLC is capable of this.
To fix this game, they will have to completely revise the content of the open world. Completely revise the entire story campaign and rewrite it.
NOBODY WILL DO THIS! So this game is doomed.