It's difficult to say for certain, but the upcoming Halo 4 may offer a variety of space and sea vehicles in addition to the ground vehicles and aircraft currently confirmed to appear in the game. Granted, the Halo universe has always offered both space and seabound vehicles, but it may be the first time any of them will be usable outside of the singleplayer campaign.
The speculation that Halo 4 may offer space and sea vehicles comes from the description of the Operator specialization, which reads as follows [link]:
Spartan optimization for the operation and control of a wide range of vehicles: space, air, ground and sea.
The Wheelman armor mod gives Spartans the ability to coax every bit of stamina and durability out of vehicles they are piloting.
There's a strong chance that the description of the Operator is simply there as flavor text, given that the Specialization armor systems don't actually affect gameplay outside of the armor mods. This may be similar to the description of the EVA variant in Halo 3, which referred to "increase mobility in zero-gravity situations" despite the fact that there were no zero- or low-gravity maps in the game.
Regardless of whether the armor refers to real space and sea vehicles, there's little doubt that fans of the game—ourselves included—would love for 343 Industries to give these settings some consideration in the future, if not in Halo 4.