This may be for a future Draconomicon, or even a reboot of "Council of Wyrms" based in Chris Perkins' (homebrew setting) Iomandra. I advice to allow some space to add later the rest of all true dragons, even the forgotten from previous editions (for example the brainstealer, the cobra dragon or the rainbow dragon). It shouldn't be difficult if we add more planets in the same crystal sphere.
I wish the return of Dragonlance, and I guess this should be a logic step because this franchise in the right hands may become one of the best cash-cows by Hasbro. WotC should explain that door still is open but we have to await a little time more.
You know more of one player wants to be a dragon rider, or a pokemon-trainer/digimon tamer with dragons as monster pets. And always there is a player who wants something more exotic, for example a no-core dragon as monster ally: imperial lung, planar, gem, outer(stellar, radiant, sun, moon..).
Wouldn't you like dragonborn subraces based in no-core dragons? Nor metallic neither chromatic, but other type, as lungs, planar, gem, outer...
I miss the dragons as monster classes from Dragon magazine.