Use 'in the air' when an outcome is still being decided or is unknown. The decision for the new team leader is still in the air.
Pro Tip 2/3
Avoid Assumptions
Don't presume a final result when you hear 'in the air', as things can change. Although the merger talks are in the air, employees are advised to continue as usual.
Pro Tip 3/3
Temporary State
'In the air' often implies a situation is in a temporary state and will be resolved. The future of the project is up in the air until we secure more funding.