Certainly, the business and economics are different from ocean cruises (especially labor costs) - but I still think that river itineraries could be a profitable addition to Princess, HAL or Celebrity/RCI.
By the way, I'm not necessarily a proponent of this (I'd appreciate payment terms more in line with US standards, but I'd hate to see creeping fees) - I'm just wondering why it hasn't happened yet or if it is likely to occur soon.
Upcoming Queen Mary 2 - RT N Atlantic crossing - 2018
Queen Mary 2 - RT crossing + Bruges - 2017, Queen Mary 2 - N Atlantic crossing - 2016, Celebrity Infinity - S. America - 2015,
Star Princess - Pacific repo - 2015, AMACello - Rhine - 2013, Norwegian Spirit - W Caribbean - 2011,
Crystal Serenity - E Med - 2010, Queen Mary 2 - Canada - 2009, Eurodam - Baltics - 2009,
Queen Mary 2 - N Atlantic crossing - 2008, Queen Elizabeth 2 - W Med - 2008, Amsterdam - Alaska - 2007,
Norwegian Sun - W Caribbean - 2007, Voyager of the Seas - Bermuda - 2005, Star Princess - Mexico - 2002,
Carnival Spirit - Pacific repo - 2001, Norwegian Majesty - S Caribbean - 2001, Rembrandt - Canada - 2000,
Seabourn Sun - SF cruise to nowhere - 2000, Queen Elizabeth 2 - N Atlantic crossing - 1999, Zenith - Bermuda - 1998,
Queen Elizabeth 2 - Panama Canal - 1997, Celebrity Century - W Caribbean - 1996, Nieuw Amsterdam - Alaska - 1993,
Nieuw Amsterdam - Pacific repo - 1993, Crown Princess - E Caribbean - 1991, Westerdam - Mexico repo - 1990,
Queen Elizabeth 2 - Hawaii - 1989, Cunard Princess - Pacific repo - 1987