Grifball will be added to Halo 5 later this month. We'll have more details as they're made available.
One of the other ball-based modes coming to Halo 5 is an "upgraded" version of Neutral Bomb Assault that, for Halo 5, will be called Assault.
"The core rules are more or less unchanged: a ball spawns on the center line of the map and players must deliver the ball to the enemy team's goal and it explodes (Woot!). That's about where the similarities end," Grossman said. "We went back to the drawing board on when and where the ball spawns, the abilities of the ball carrier, and the arming process itself. When the game starts, the ball will spawn at a unique location each time it spawns throughout the match. The order of locations is always fixed so players can learn to predict the next spawn. Once a team establishes control of the spawn location, they can pick up the ball."
Grossman went on to say that carrying the ball in past Halo 5 games "felt like work" for some players instead of being fun. In Halo 5, things will hopefully be different.
"We tried a lot of different tweaks from changing movement speed, changing the way navpoints work, modifying damage resistance, disabling ball throwing, and more. Eventually, we decided that there were three key components to the ball carrier: they needed to win melee fights, be able to survive while arming the ball, and be able to make it to the enemy base undetected," he said. "To meet these goals, we made the melee attack with the ball an instant kill, gave the carrier an extra thrust, and implemented the same 'Spotting' mechanic present in Capture the Flag. While arming the ball, the carrier can use their two thrusts stay alive or to close the gap on the enemy and beat them down. We think that the new carrier mechanics will give players a new skill to learn and enable a skilled ball carrier to win the game for their team."