My guess is that online rewards will be:

*A special flying mount (something along the lines of the FFXIII birds, maybe?)
*A Kain Highwind minion (seeing as Dragoons are the main theme of the expansion)
*Abel's Lance replica

For the physical copies, it may be:

*A map of Eorzea, including future areas (Ala Mhigo, Garlemald, etc.)
*An Ishgardian medallion
*A figurine of either Bismarck or Ravana