Imagine you, the player, only gradually discovers your character's draconic abilities rather than always getting the same ones by the book.
For example, before 10th level your DD instead of a Fire breath weapon gets a breath weapon that deals a bit of acid damage and some weak Dragon Bile poison (deals a strength penalty). Then at tenth level the breath weapon changes into one of the main types (acid, or fire etc) and the damage immunity gained is something that matches.
As the character goes up in epic levels it gains other random
draconic spell like abilities at levels maybe 15, 20, 25 and 30. Abilities should relate to the type of dragon the character turns out to be descended from. There should be a good collection of such abilities so no two PC DDs will likely end up with all the same the same abilities even if they are of the same dragon type.
In part to help keep each DD unique the abilities gained should increase in power not every level but on each level when a new power is gained so for instance if at level 15 your characters gets Cure Wounds then at level 20 the amount healed by that power would dramatically improve and another spell like ability would be gained, but if it first gained the cure power at level 20 it would not improve until level 25 etc.
Such progressions of once-per-day powers might be something roughly like these:
Fire Storm: for (6d6, 9d6, 12d6, 15d6)
Cure Wounds: ( 8d12, 12d12, 16d12, Heal)
Restoration: (Lesser Restoration, Restoration, +Remove Poison/Disease, +Removes Curses and some other effects)
Shadows: Shadow Conjuration, Greater Shadow Conjuration, Shades, Weird
Death: Negative Energy Burst, Enervation, Death Spell, Finger of Death
Alternate Breath Weapon: the DD's breath weapon can have an alternate effect chosen on the fly ( eg instead of Fire Damage it may cause Sleep, Slow, Negative Energy etc depending on the type of dragon)
Paralysis: Hold Person, Dominate Person, Hold Monster, Dominate Monster
Sight: See invisible, +Clairaudience/clairvoyance, True Seeing, +Premonition
Aura of Fear: as per the Draconic Aura of Fear with DD level used instead of Hit Dice for DC and duration
Disjunction : like Mordenkainen's Disjunction but with it's power stepping through 4 levels only reaching the full power of the 9th level spell at level 4 (at 30th level)
Flame Strike: (6d6, 9d6, 12d6, 15d6)
Chromatic: Prismatic Spray effect that increases in power over 4 levels like the Disjunction
Spell Resistance: 20, 24, 28, 32 for a duration of 1,2,3,4 turns
So for example a 30th level DD might end up with Heal spell (the 4th Level Cure Wounds power), Death Spell (the 3rd level Death power), Greater Shadow Conjuration (the 2nd level Shadow power) and a weak FireStorm (6d6 1st level firestorm power). Such a DD would still have its 12d10 breath weapon but it might be some damage other than Fire.
I think it might be fitting too if the wings were gained at 10th level and came with some small use - such as immunity to the Grease spell and maybe maybe something like a small bonus to Tumble and Discipline (the wings might make it harder to knock them down and less likely to slip on the grease or ice, harder to lose balance etc).
Another change might be to let DDs take as epic bonus feats more feats geared towards Mages like the epic spells (assuming of course they otherwise qualify for said feats) since they already get access to auto-meta-magic feats and it might be nice to encourage high level Mage/RDD builds. I could also see adding in some Bard, Monk and Rogue epic feats in the same way to encourage more build diversity.
I think all of this could be done with a bit of scripting and a few 2DA changes.