Bungie will Have 343 Cover all Halo Community Based Services
As of March 31 of this year, Bungie will no longer host any Halo services on Bungie.net (according to this article on Joystiq). All current Halo data will now be handled and transferred over to 343. When that happens, 343 will accept all responsible of handling the information Bungie will no longer be able to update game stats, player service records, host any new user generated content, or operate any more of the Bungie Pro services. Any type of replacement functionality for the community or the game will be hosted by Halo Waypoint on halo.xbox.com.
It should be noted that Bungie doesn't mention if functionality will be replaced, but that seems unlikely for Microsoft to allow Halo's community features to disappear completely as they are the bread and butter of the community franchise. Knowing how upset people would be if people weren't able to show off their tricks and great shots, I doubt Microsoft would do such a thing.