I think we'll see more "packages" created. I agree with Thomas -more pay as you go - and I think they'll be in the form of packages.
An entertainment package would include all the shows and x number of drinks.
A shore excursion package would include a shore excursion in every port.
Casino package - x number of dollars in the casino, etc.
A family package might include x number of soft drink cards, a family shore excursion and a t-shirt or two - maybe even babysitting hours.
I think the cruiselines will figure out that pay as you go will tick people off, but if packaged well, people will feel as though they are getting a "deal."
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