Alrighty then.... In my opinion, I think that it should just be halo 2 servers rebooted on Xbox One and/if 360.... Or just upgrade the graphics in general, and this time, use the ACTUAL Halo 2 multiplayer not an upgrade for Halo 4 or Halo: Next (previous, nor present), because I'm sure veterans would love to see the matchmaking experience they grew up with and of course the new to touch one of the most gorgeous pieces of halo artillery.
Also do NOT set skulls to be activated in the beginning... Halo 2 was fun to scavenge for a one time use. And no Easter egg removal, if there is, they better be replaced by something very impressive.