At the end of 6.55, cutscene #4 of "The Coming Dawn", we see Urianger and Thancred, acting mysteriously with their own letter, presumably from a competing candidate for the throne. This letter actually seems to be written in Eorzean lettering, though it is very small.
What could this mysterious letter say?
Some existing speculation:
Paragraph 3, line 1 seems to start with "We're pleased to announce that"
Paragraph 4, line 4 starts with some capitalized text that looks like "Wings of the Goddess"