listening to this story, my most emotional reaction was heartfelt agreement that the game becomes only fun for one person. Inevitably, you reach a point where it's one to one, and it's pretty clear who the loser will be. It can still take a very long time for that person to go ahead and lose.
Therefore, I think the loser should be allowed a fighting chance. Considering this is about fighting a monopoly - a very powerful entity that has all the money in a game that is all about money - the person in second place will have to resort to crime. Player 2 can recruit people eliminated in the earlier hours of the game as thugs, or the players eliminated earlier can form an organized crime family. Or two organized crime rings, which battle against each other in support of player 1 and player 2. These guys benefit play 2 in obvious ways - they can burn down hotels! They can shoot up houses! They can start a smear campaign so no one wants to do business with player 1! They benefit player 1 by offering muscle against player 2's thugs.
But additionally, they benefit themselves. Obviously they can charge ever increasing rates to player 1 and player 2, depending on the stakes. This money can put them back in the game. In fact, through strategy and ruthlessness, players who were out early can become the winners!
Of course, this would take much longer to play than normal Monopoly. But hey, it's an online world. On the internet, a days-long game isn't exactly unheard of.

Keep the pieces, the money, the cards, even the board. But add two new pieces to represent factions of players that reinstate themselves - a gun and a book of matches.

Shannon