Yes, airlines can change flight schedules and I have been affected by this several times. If your flight to Orlando is changed again and you know you won't be able to make the revised flight time, just give the airlines a call to let them know that you will be on a cruise ship and cannot make it -- and they are usually pretty good about changing it to a later time without charge.
You can find out while on the ship by checking the airline's Web site, or by registering for updates via your cell phone number with the airline before you leave. When you pull into Port Canaveral and have no messages on your cell phone, there would have been no changes. If you do have a message, you will find out before you get to the airport.
One thing worth looking into now is that changes in flight times will occasionally result in changes in your seat assignments. So, call the airline to ensure that your seats are still together. It's better than waiting until you get to the airport next week.