Saying that the game is dying is an overstatement I mean it started dying a long time ago but we are more in a stalemate now where no one joins the community and no one leaves and if someone actually leaves there is like 1 new person to replace him/her, though those that leave the community usually comes back rather quickly.
But what the reasons for this game not growing is things that have been mentioned before Warband is old, the lack of updates and the price.