The expansion should allow for the larger cruiseships to go through the canal. I don't think that a big change in cruising will occur because there might not be enough demand for the larger ships on the Pacific Coast.
Carnival Liberty New Year's Eve 2007
Liberty of the Seas 5/2008+11/2009
Allure 1/16/ 2011
I agree with Manuel. There may be some increase, but most trans-canal cruises I see are 14 or 15 day cruises between US ports. That's outside many people's vacation window.
A Bad Day At Sea [with power] Always Beats A Good Day At Work
Alaska 2014 - haven't picked a cruise yet
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, Caribbean 2013
Probably the biggest change will be the increased cruise fares for these trips.
Building those new locks cost a great deal of money. Somebody has to pay for them.
When my ship went through in April (one way), we paid just over $400,000.
The Canal Authority is predicting a 20% price increase next year.