Under normal circumstances you should be fine. Usually, early disembarkation can get off as early as 7:30-7:45. Taxis will be waiting and it only takes 10-15 minutes to get to the airport as it's only about 3 miles away. So if all works according to plan, you should be able to get to the airport by 8:30, which is plenty of time.
As for if you miss your flight due to a delay in getting to the airport, if I remember right, Southwest is pretty lenient about it provided you give them notice as soon as possible letting them know you're going to miss your intended flight. This may have changed, so I would suggest contacting SW directly and asking them the question to make sure you get the latest policy.
But to take away all hassle and stress, I also highly recommend you purchase travel insurance. You always hope it's a waste of your money, but if you need it, you're sure damn glad you've got it.
__________________ Travel Agent/Cruise Specialist w/13 yrs exp and 48 Cruises on 11 cruise lines! Favorites: Paul Gauguin - Tahiti: Uniworld River Cruises - Europe; Celebrity Solstice-class ships; Holland America - 12-nights Baltics & Russia; RCCL - 14-nights Greek Isles, Turkey, & Croatia; Holland America - 14-day Alaskan cruisetour; 10-night Canada/New England cruise; 21 days Hawaii w/7-night NCL cruise; Oceania - 25 days in Asia; more than 3 months touring Europe by train. And many all-inclusive resorts!
I have seen elsewhere that due to sequester that there may be fewer TSA and USBP agents available clear the ship and airport security might both take longer.
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