There is no doubt that many were rather anxious when Halo 4 leaked. Seeing the official reveal trailer only furthered said hesitation, especially when you consider it's a whole new trilogy. Perhaps it's because Halo 3 seemed to round off Master Chief's story so well, regardless of the fact that it ended with a cliffhanger, or maybe it's because Halo: Reach brought so much to the series that it's quite difficult to imagine where to go from there. That is, if you're looking at the Halo series from a strictly multiplayer perspective. Strange as it may seem, Halo has been a series largely defined and directed by its story campaign. If 343 is planning on making any major changes to the series, it may be best to look into how they plan on developing Master Chief as a character.
Halo 4 will be picking off right after the events of Halo 3 with Master Chief supposedly confronting some sort of ancient evil trying to annihilate all life forms. Cortana will be along for the ride and if we're to take the E3 cinematic release trailer at face value, players can look forward to being able to actively use a jet-pack and possibly a pistol that shoots explosive rounds. There isn't a lot to go off on, but those familiar with the lore of Halo know that there are a few avenues that 343 Industries can explore.
The Forerunners will come to the minds of most Halo fans since they're one of the few alien races in the Halo universe which players really never come into contact with. Not to mention, they're the ones responsible for all those nifty rings that contain the Flood. Their technology is both massive and complex almost beyond understanding "” although 343 may run the risk of upsetting hardcore lore/Bungie fans depending on how they interpret the race, it's definitely a possibility.
What is more likely is that Master Chief will encounter yet another alien race. Considering the setup that Bungie left at the end of Halo 3 and the far more aggressive start that Halo 4's trailer appears to be taking, it would be a much better choice to have him fighting against an entirely different alien society. Most of Halo's iconic moments are tied down to the fact that players are constantly struggling on alien worlds. They may be mostly humanoid but they are still strange and exotic in design. The Elites, aliens which began as mid-level enemies for the franchise, have rapidly evolved to become one of the most identifiable science fiction races out there and have rightfully earned positions as playable characters in a variety of multiplayer modes. Halo's main characters have all undoubtedly been human, but with the roots of their conflicts based upon a massive alien political hierarchy, it only makes sense that 343 would attempt to expand the universe rather than attempt to shape what's already been made.
A setting change doesn't simply mean new enemies to kill either, but new weapons as well. How can 343 rationalize using the same old alien technology if the struggle against the aliens using the weaponry is over? With the core mechanics of Halo mostly unchanged since it's inception, weaponry and level design will be the deciding factor when it comes to how well received a new Halo trilogy might be. It's not about making the game easier or more difficult, it's about making sure the brand is still something fans will recognize and accept even in the hands of another developer. There is currently no other FPS quite like Halo on the market and considering the state of the FPS genre today, that's a pretty impressive feat.
With a predicted date of 'Holiday 2012' we've got a long way to go before more information regarding Halo 4 is released, but considering this year's E3, it'll be hard to say I'm approaching this new chapter without any sort of anticipation. If anything, 343 should be given the benefit of the doubt, although it would have been nice to see them continue on the Halo saga without the help of Master Chief. If Bungie was able to make an incredibly successful title without their main Spartan, why can't they? Perhaps it's a harsh question and maybe Microsoft didn't leave them any other choice, but for the time being lets just hope that there's enough creativity in this relatively untested developer to last one new Halo game, let alone another three.