I like your theory that there could be a possibility that Dumat is still alive. Maybe he was alive up until the death of the Archdemon/Urthemiel and died at Fort Drakon. Maybe he survived the Fifth Blight in another form? We have little information on both The Old Gods and the Maker, and there are indications that the Maker may well remain a mystery. My thoughts are that Dumat is not the Maker, but he still could have had a hand in a lot of the situations that go back a thousand years when he was transformed into an Archdemon. I get the feeling that if Dumat was a player, there were other players in this play, some of whom did not even realise they were being used.
Quote from David Gaider:
The cult of the Old Gods (I don't call it "the Tevinter religion" mainly because that, to me, speaks of the Imperial Chantry -- which is based in today's Tevinter Imperium) didn't contradict the existence of the Maker. Quite the opposite. The people of ancient Tevinter were aware of the existence of the Golden City and ascribed to "the Maker" (though this Creator was not called this until the appearance of the Chantry) the creation of the world. The Old Gods were not creators, though they were supposedly also not created. The Old Gods were outside of the Creator's Plan and showed up to whisper to mankind and teach them magic. According to the Chantry, they turned mankind away from their regard for a remote Creator (who ruled remotely and never interacted with his own creations) and that this is what made the Creator abandon the Golden City... though there is argument that the cult believed the Creator had abandoned it long before and that they were adrift, rescued by the Old Gods. Modern sages say that this is attempt to explain the hardships that the early human civilizations faced, and not evidence of the Maker actually being absent.
http://dragonage.wik...ki/Grey_Wardens The Grey wardens, The five Blights and their participation.
http://dragonage.wik...m/wiki/Old_Gods The Old gods and their relationship to Magisters and Darkspawn
Quote from it:
What the Old Gods actually are and their relation to the Maker is very mysterious. It is unknown if one predates the other. The Old Gods are not creators and although they exist outside the Chantry's pantheon, the people of ancient Tevinter do attribute the creation of the world to the Maker, although by a different name.[The Chantry teaches that the Old Gods were false deities. They turned mortals from worship of the Maker, recognized as the "First Sin". As a result, the Maker imprisoned them underground. Their minds continued to roam the Fade like any other dreaming individuals' mind would, and they were able to contact the Magistersand teach them to use magic in hope that the magisters might free them. It was for this reason that the magisters entered the Golden City in a failed attempt to usurp the Maker's throne, inadvertently causing the First Blight.
http://dragonage.wik...tinel_armor_set Armour worn by an unnamed Anderfel Warrior who reportedly killed Dumat.
http://dragonage.wik...ki/First_Blight Dumat's corruption, his first Slaying and what came after.
Quote from it :
The Grey Wardens met with great success in their early years. A group of Ander soldiers even managed to slay Dumat while he was on the run from a Warden offensive. The celebrations were cut short when Dumat returned unharmed. In the years that followed, scholars learned that the Archdemon's death had only forced its soul to relocate into the body of the nearest darkspawn. Eventually it was proposed that if Dumat were slain by a Grey Warden, then his spirit would rush into the Warden's body. Unlike the darkspawn, a Warden's body already has a soul, and the resulting paradox would destroy both Warden and Archdemon
The Grey Wardens formed a formidable force made up largely of Tevinter, Rivaini and Ciriane soldiers. In a coordinated attack, they slew Dumat and routed the darkspawn forces at the Battle of the Silent Plains in -203 Ancient (992 TE). A third of all the human armies fell in the battle.
Dumat did not return in the years that followed. Although the darkspawn horde remained large in number and the battles persisted, without the Archdemon to lead them, they became disorganized and by -195 (1000 TE) were forced underground. For the surface world, the Blight was over.