Halo 4 and MCC really did put the series in a place that is probably irrecoverable. Halo 4 with it trying to be like CoD after YEARS of the fan base saying they did not want this and complaining that Reach was too far away from what made Halo great gameplay wise. Which is quite shocking it happened because 343 became the caretakers of the franchise during each and HEARD those complaints, so much so they even released an update that fixed issues with the game. It wasn't implemented everywhere, but still, they heard us.
But I guess that's why there is a difference between hearing and listening.
MCC is and probably will be the biggest AAA fuck up this generation. The one game that could've given the fan base some good will and hold over until Halo 5, and return Halo from the dark recesses that Halo 4 put it in, it completely botched everything.
Everything.
It was and still is a joke. After that fuck up, why would anyone, not just the hardcore, but the casual, have faith in 343? Especially, espicially after Destiny released.
And I think that is our answer. After years of fuck ups, the original dev releasing their brand new IP on not just Xbox, but the now more popular and powerful console, fans left for a different pasture. Why buy Halo 5 when I can play this MMO-lite that demands my attention, or even, why should I buy an Xbox One for Halo 5?
It also doesn't help that this game is not casual friendly. It is a very competitive game and there is only 2 modes that you can fuck around in, and even those get boring because there is little to do.
Halo 5 right now is not a game for Average Joe to pick up. Maybe 6 months from now if 343 get their shit together on post launch support, it'll be safe, but right now, it looks like the only ones that would buy Halo 5 are the ones that are already fans.