I would rather see this game kept as it is, if it were to turn into an mmo, that would defeat the purpose of those buying, or bought, a DA and the one time payment. As well as that I would wonder how the classes would be made to fit into the mmo, would it be like AQW, where the classes have 4 skills, or will it have the DF fighting system where you are brought into a fight and have the 14 skills. Those are my concerns with turning this into an mmo game.
A 3D version of this game does make me curious how it would work, but I would rather see it in 2D, I mean... look at the artwork we have ^^
A dragon/mech game does sound very interesting and I would like to see how that would turn out, just not in mmo style :p
As for the epic duel, would this just affect the pvp system in DF or the whole game... If just for pvp then I do like the idea of it, does make it sound rather fun. On the other hand, however, that just depends on what would be changed XD
All in all, I would rather keep dragonfable the way it is, its fun, its enjoyable and it gives me smileyface =)
That does not mean I am not up for a change, so long as the changes are good changes XD