This is a very oft-discussed and contraversial point on the Waypoint forums and has been ever since Bungie put Armor Abilities in Reach. "Enhanced mobility," by any other name is undoubtedly game-altering; the argument comes in around whether it's an enhancement or if it just throws the whole Halo formula off.
I started off firmly in the camp of believing that Armor Abilities and features like Spartan Abilities were enhancements to the game rather than demerits; I still agree with this idea on a strictly PvE and Campaign level. As long as enhanced mobility options are well designed and comfortable and intuitive to execute, they lend serious credibility to the feeling that you're a bad-Yoink! - future super soldier.
On the other hand, though: enhanced mobility of any stripe deeply complicates and throws a wrench into competitively balancing a fun and meaningful PvP Halo experience. Traditionally, Halo multi-player was a mid-paced game featuring a very strong but not overly complex sandbox identity. Movement was vertical and directional in about equal measure (Jumps were critical for evasion/mixups/etc.) The golden triangle as defined by Bungie at the time said Halo was a balance between Gunplay, Grenades, and Melee. But what wasn't as clear at the time was how critical movement dynamics played into the balance and feel of the game, especially in regard to pacing.
So Bungie and 343i have given it an honest shot, by now. Bungie tried to make Reach feel balanced by making Sprint one of several bizarre (some way more gamebreaking) Armor Abilities which you could equip. Halo 4 gave everyone sprint and kept the formula of another optional armor ability. Halo 5 went for the gold in expirimenting with Armor Abilities by standardizing the Spartan Abilities as we know them now, and making them base traits for every player. I remember there being a marketing push that this was in an effort to make the balance more even and "traditional" by removing alternate player advantage/disadvantage from AA's. It sort of did this, but it created as many or more problems than it solved in other areas (map design, weapon balancing, etc.).
Halo's sandbox has never been about having the fanciest variety of options to use as a player (the original DOOM games in some ways exceed Halo CE's sandbox complexity at least with regard to weapons and movement pacing). Halo has always been about having a distinctive, intermediately complex sandbox and moderate player movement speed and mobility, which creates a fairly even-keeled competitive MP environment.
This relative simplicity made Halo the competitive phenomenon it was in the mid to late 00's. Abandoning it is a huge reason for the decline of the series' popularity.
So, will it come back in Infinite? Likely in some form or another. It's definitely hard to put this particular genie back in the proverbial bottle, given how many players like the basic idea and appeal of enhanced player mobility (again, admittedly I like it in PvE modes.) But if they want to make the Halo game that will remind everyone of the glory days of the series, they'll need to minimize these mobility mechanics and re-simplify the weapons sandbox.
TL;DR (I got pretty carried away there!) :
Halo 5 threw enhanced mobility at the wall in the biggest way yet, and it didn't particularly make for a better tuned/balanced MP (Certainly not compared to classic Halo). They can go back to the well on it and hope that this time it's favorably received instead of a huge point of contention. Or they can re-simplify and try to get Halo back to its status-quo for feel-of-play.