This announcement doesn't surprise me for a number of reasons. I know that bookings have been soft for Europe this year even with putting a smaller ship in Europe.
Carnival's core demographic are not people who would make Europe their first choice in cruising. Yes: I know that many Carnival cruisers love to sail in Europe but not enough to make it as profitable as they would like. I greatly enjoyed the Carnival Breeze last year.
Carnival recently opened an office in Singapore and will be expanding to the Asian market. I am interested to see how this works out. With Asia's emerging middle class I see this as a great opportunity for all of the North American cruise lines. They will have to target the Asian market because, in my observations, it seems that U.S. cruisers balk at paying more than three figures for airfare. Once the airfare goes over $1,000 people look for alternative cruises and destinations.