Making Dragonfire Inspiration less dragon-y

[claypigeons]

Simply put, what measures could a DM take to make dragonfire inspiration less about dragons?

Would a feat requirement still be required for balance? Perhaps another feat to change the damage type?

[Waker]

Well, you could expand it to include creatures with elemental subtypes or other bloodlines, like Genasi for instance. Alternatively you could require a feat tax like Elemental Substitution. Maybe speaking the language of the elemental in question, like Terran for Acid, Ignin for Fire, etc.

[ExLibrisMortis]

There are other elemental entities. For example, djinn, efreet, marid and dao, collectively known as genies (air, fire, water, earth respectively). Any outsider (native) may have a genie bloodline, thus being able to use Geniefire Inspiration. Similar refluffs can be used for people with fey blood, devil blood, or even undead/Pelorites (Blackfire/Sunfire Inspiration?).