Actually, there is a way. Zandalor was left untouched in the end, you didnt meet him after Aleroth, except the memory, but that doesn`t count. He could brake you free. Since, i think a new character, i agree, wouldn`t be the same, there`d be no point, no meaning to him.
How would Zandalor know of the fate of the Dragon Knight or even more where is he being sealed? And what Kein said he doesn't have the equipment to venture to the hall of echoes. I just remembered something. The old true dragon you met tells you that you are THE LAST DRAGON KNIGHT. So Talana must be dead :| If you continue the story with new non dragon, towerless character it would be kinda dumb :| All that effort to obtain the d.stone, the b. tower and the servants would go to waste!