I for one wouldn't like to see any more dragons. Believe me, too many dragons can and will become boring after a certain time (see Heroes 5). I think there's a good balance of dragons in the mod right now: Acheron guarding the horde (what's a fantasy setting without a dragon's horde?), Abashi the "bad guy" bearing Tebryn's rune and Eurabatres the "good guy" secretly guiding the Kuriotates.
Considering the backgrounds of Abashi and Eurabatres, an interesting idea comes to mind. If the Sheaim are led by Tebryn and Abashi is defeated, then the civilization would receive a big penalty (because Tebryn's rune is destroyed and he dies, or whatever Liches do). Similarly, if Eurabatres is defeated, something even worse happens to the Kuriotates (because the conscience that lead them through Cardith Lorda dissapears).
But, of course, seeing that these two dragons become available near the end game, after lots and lots of work, it would really not be very pleasant -- gameplay wise -- for the player to suddenly find himself crippled because the dragon died.
Just and idea I thought I'd share...
P.S. This is from the Round Table forum and I find it very useful: