The final true ending for Halo 2 was on April 14 2010, April 15 for some...
That day the best online competitive FPS to ever hit a console/PC with internet capabilities for gamers to interact was shut down, and Halo never regained its glory even to this very day.
H3 was not a good follower to the level of competition H2 spawned, but it remained very competitive and has skill gap.
Reach was an utter epic FAILURE in every way that a Halo game can be.
Halo 2's true ending to me was TEAM HARDCORE CTF on Midship. I went 20-8 with 3 flag pulls, 2 captures and we won capturing all flags and opposite team scoring only 1.
Then like the ending on Terminator 2 when Arnold is lowered down to the hot lava-like boiling metal, my Spartan 2 (sniff sniff) with his right hand on a BR-55 (sniff sniff) and his left arm raised high with pride (sniff ...sorry.. this is hard for me to say.....sniff) his left hand motioned a "Thumbs Up" gesture then some static on the screen then a small dot....and blip..total darkness, connection lost, unable to connect to xbox live. (cue the sad Terminator 2 song..bumbum..bum..bumbum........bumbum..bum..bumbum.)
And now Halo has been in total darkness since that day with H3 failing to recapture the glory and REACH being the final nail on the coffin of the giant franchise. Yes sir that ending doesn't get any sadder than that. Where were all of you on the day The Great XBL KING died?