God I wish CoD died off when it was supposed to following Infinite Warfare. But I am glad that they decided to go back to the roots of CoD due to the latest game being probably the worst received game yet from them. CoD and gamers who allowed CoD to flourish like it did post CoD 4 are the reason that the industry is in decline, and why companies that actually put proper work in to their games gets worse sales. Like you said, the world isn't waiting for Master Chief any more. Why wait when you can play the same game with a new skin every year and call it a new experience?
Maybe a campaign only would work , but the multi-player components of Halo have to be given room to breath. Halo 2 and 3 lasted years on the strength of their multi-player alone , what happens when they go to a yearly release schedule and the next Halo 2 hit happens for the series? Do you continue making Halo games every year knowing either ; it will be ignored by a large part of the community , or it will kill any momentum the current game has building. Halo games don't need to be released on a yearly schedule and don't need to drop like clockwork, but they do need to appear more often than once every 3 years. There's too much potential for great games and great stories to be told. Honestly, a 3 year wait kills the hype, because the world isn't waiting on Master Chief to save it anymore. Like Locke said to Osiris on Geneis, "Don't stop! Cortana is waiting for us," someone needs to tell 343 and Microsoft, "Don't stop! The world isn't waiting for Master Chief." Yet it seems to be eagerly waiting for CoD: WWII and the latest Destiny DLC (smh). Something's obviously wrong here.
I don't care for CoD myself , however there is something to be said for consistent mechanics. Yes they have a new game every year , but they are developed on 3 year cycles as there are three different companies making CoD.
SledgeHammer , Treyarch , and Infinity Ward have done a very good job of keeping the basic mechanics consistent across all releases with minor variations. Their fan base has been building for each different company so that , I.W. has there own hardcore fans , Treyarch has there Bl.OPs fans , etc.... , Halo had those fans , until consistency went the way of the Dodo. Now every Halo game handles and feels different and has new controls to learn , this turns fans off by and large. Halo CE to 3 all had different elements but felt and played fundamentally the same , minus hit scan and equipment. Reach , 4 , and 5 have turned the feel of the game on its' ear and now they are floundering for a direction. Once Halo is back on solid footing , and 343 can say these are the staples (move speed , TTK , aim mechanic , standard abilities [what are and are not]) , then maybe you could bring in another company and shorten the development cycle , until then you are only asking for trouble.