Offing
Yes, offing is a responsible, adult word! And not just in the phrase “in the offing” which is now perhaps its most common usage. It is actually a nautical term …
1. The part of the visible sea distant from the shore or beyond the anchoring ground.
2. A position at a distance off the shore.

Hence, by analogy to a ship some way off shore but visible, that phrase “in the offing” meaning something that is close-ish to hand and yet some way distant.
The OED gives the first recorded use in 1627.