Is there another way "The Pardoner's Tale" could end and still get his main idea across? If so, how? If not, why not?

I don't think it should end any other way because the Pardoner's intent was to impart a morality and universal message about life and death. At the center of the tale, there is a search for somebody called “Death” which, naturally, does not find the person “Death”, but death itself. It is a successful – but ultimately unsuccessful – search. All that is left over at the center of the Tales is the bushels of gold, sitting under a tree unclaimed. The root of the tale, as its moral similarly suggests about the root of evil, is money: and money was, to a medieval reader, known to be a spiritual "death". Notably, moreover, in the tale, both “gold” and “death” shift from metaphor to reality and back again; a neat reminder of the ability of the Tales to evade our grasp, raising difficult questions without ever answering them.