@Arokh
Dragons are immortal and if you read the books in Divinity 2, it states that some people even thought they are gods who created the world. The Patriarch claims that his name gives birth to new creations...so it could be true.
Dragon Knights however are part human and part Divine. They would live for thousands of years. When you speak to Simon The Philosopher, he says he envies you because of your mind as a dragon and because of how long you would live for (I swear he says this). In any case, Dragon Knights became Dragon Knights when Maxos made them so. When Maxos vanished thousands and thousands of years ago and his Battle Tower was locked by magic, the Dragon Knights that remained were the last and eventually they were hunted down one by one. Talana remained until Divinity 2 which is THOUSANDS of years later from the time of Maxos. I think it's Lovis that states that Dragon Knights aren't immortal.
@Wotan
"And then the Dragon Slayers killed you, lol"
LOL, I found this line funny.
As for the PC's fate...I personally don't know what Larian will do. I think they will leave the PC's fate unknown (much like the PC of Beyond Divinity) as you said. I don't however think the story would last to Divine Divinity and beyond because we didn't see Dragon Knights there and it wouldn't make sense for The New Dragon Knight to be fighting his/her own war (choosing to be good or bad) while The Black Ring fought against Aleroth and the other races. It not only disagrees with the lore but it wouldn't make sense.
