The spell database contains an interesting discarded Dracthyr racial ability that would allow them to fly without a mount.

[TEMP] Flight is an interesting entry that remains in the databases even though the Dracthyr have ended up with entirely different racials.

It suggests that at some point during testing, the WoW team played with the idea of letting Dracthyr fly without a flying mount, which makes perfect sense. Unfortunately, the idea was probably scrapped for an unknown reason, maybe in favor of Soar.

[TEMP] Flight – Spread your wings, increasing movement speed by 150% and allowing you to fly. Cannot use in combat (Instant, 1 sec cooldown)

Source: Reddit