Future endeavours is a term used in the military to talk about future missions. Employed by Marines, Navy personnel, and other services.
The military is no different from any corporation out there – with a limited budget, everything has its priorities. One of the ways that ‘stuff’ like repairs and replacement equipment for existing gear (for example: ships) gets done quicker is to plan for “future endeavours”. The term itself doesn’t mean much more than “projects planned for after this one’s completed,” which covers anything from training to longer-term infrastructure projects.