Lol at the no end game content... Do you realize we can say this with pretty much ALL the single player/coop games in history?
Mario, you finish the game, tried to break some score records, then what.
Doom, you finish the story, you,ve got your BFG and beat the boss at the highest level, then what?
StarCraft, you finish the campaign, you beat the hardest computer setting, then what?
Skyrim, you finish the campaign, you beat every monster and boss in the game, you are now the kind of the world, now what?
The only way for a video game to stay alive forever is to have competitive PVP (Street Fighter, Battlefield, Starcraft multiplayer) or have the game add constant new content (MMOs, Mod community).