I already have Halo 2, and I've played it countless times. The only reason I bought CE Anniversary was because I never played the original. Since I already own Halo 2, I see no reason to get Halo 2 Anniversary. Give me Halo 5.
Plus, 343 should be focusing all their efforts on making Halo 5, not remaking previous Halos. Next thing we know everyone is going to be asking for Halo 3 Anniversary.
They need to take their time with Halo 5, and I don't see it releasing before fall of 2014, at the absolute earliest. So give us a Halo 2 remake in the meantime.
I can just imagine it being one of the final presentations at Microsoft's E3 event: the lights dim, a trailer plays, and it turns out to be an older Halo 2 trailer with the remade graphics: then they announce Halo 2 Anniversary (or whatever the title would be), set to release fall of 2013. Maybe it would be a launch title for the Next Xbox? Hell, I'd take it even if it was just for the 360.
Will it happen? Most likely not. But we all live in hope. I'd be absolutely thrilled.
IRON MAIDEN IS MY RELIGION! Gamertag: Demigod Elessar
Basing this off of how Halo CEA was treated, Halo2 Anniversary would just be a single player remake, and a map pack for whatever the most current Halo is at the time. Without Halo 2's original multiplayer experience, there's not enough of a reason to want a Halo 2 HD remake over a completely new Halo 5 game.