Halo 2 PC Multiplayer Servers are set to close permanently.

The decision is made and halo 2 multiplayer experience will come  to an end.

Microsoft, reported that the Multiplayer servers will close on February 15, 2013, followed by the statement:

"We’ve been monitoring the population for months, and it’s been peaking consistently at approximately 20 players or less. Those that own this game can continue to enjoy Multiplayer over LAN after that date; however our network services will be turned off at that time. We love you, Halo 2 PC, and you will live forever in our hearts."

 However, dedicated private servers may keep the online experience alive. So probably if there is support by Halo 2 fans, it will not be over that easy.