I don't think we wouldn't get a toggle, but to be honest, it wouldn't surprise me if we didn't get a toggle for sprint. That being said, I do think there will be one, but the big question is...what will become the default mode of play?
One of the things that I think has plagued Halo for so long in regards to competitive online multiplayer is the default settings. Since Halo 2, competitive players have had to seek out out-side sources such as MLG to come up with a competitive standard rule set. This means starting weapons, weapons on map, player damage, all that stuff.
Halo has never been out of the box competitive (except for Halo CE), and that is one of the sole reasons we have this constant split in the overall community. Day one of Halo 5 will determine what the masses enjoy. If the game is AR/pistols, then this is going to hurt Halo 5, and automatically split the community, right off the bat.
Same thing will apply for sprint. I think regardless of the starting weapons discussion, sprint will already split the community as well.
One thing I hope for in Halo 5 is that we have out of the box competitive player vs player. I'm so tired of having to either wait for a specific playlist to fit my competitive wants, and this usually takes months, and ends up being only one playlist, which means all the other playlists in Halo become boring as snails due to the fact that they cater to one audience, which is casuals. StarCraft II doesn't do this. Nor does Street Fighter. When you boot up those games and play a multiplayer match, you're playing the same damn settings that the grand master pros are playing, plus or minus the maps.
On launch week of Halo 5, I want to see default Slayer both team and free for all have the same rules, same starting weapons, etc. In my opinion, it should be AR/BR starts across the board on all default game modes. This caters to both those who enjoy full-auto weapons and those who want a precision-based utility weapon to spawn with. During my time with the Halo 5 beta, that starting set provided the most fun and the most balance in my opinion. The game became less about trying to scavenge for a better weapon as soon as you spawn, and more about fragging the opposition and seeking out situational weapons such as DMR, SMG, or power weapons.
When it's AR/Pistol, the game becomes no different than Halo 2 SMG starts and Halo 3 AR starts. It's a race for one team to control the rifles or precision-based weapons and continually spawn kill the opposition until they get a lucky spawn to pick up a rifle and have a fair fight. This isn't fun for casuals nor the veteran players. Anyone who actually calls that fun is outright lying to themselves and won't admit that the bottom line is they actually suck at Halo and NEED that type of gameplay in order to feel good about themselves and fabricate their skill.
I don't doubt 343 will give a robust set of custom game options, but again, I'll repeat myself, I don't want to have to seek out custom games to enjoy competitive pvp of Halo 5.
If I have to go create a custom game to get competitive pvp enjoyment that's balanced, fair, competitive, skill-demanding, challenging, etc...then Halo 5 isn't doing its job correctly.
On top of this, the whole voting for maps thing in Slayer at least, should be solely on voting for a map...not weapon sets. Leave various weapon sets to separate playlists, for example, team rockets, team snipers, shotty/snipers, phantom swords, etc...all of that should NEVER be in the default team slayer playlist.
Halo 5's team slayer playlist and its rumble slayer playlist should be one single starting set of weapons across all the maps, period. If anyone disagrees with that statement, I'd love to hear your reasoning behind why it shouldn't be that way.