When Celebrity sends 5 ships to Europe for their Summer 2015 season, they will send the 91,000gt Celebrity Constellation. The ban on ships over 96,000 from the main lagoon will be effective Jan 1, 2015. This will allow her to transit the more scenic route, right through the middle of the city.
It wouldn’t surprise me to see other lines base Panamax size vessels out of Venice for the 2015 season.
Current Route ~7mi