Major world cities have immense pull and will always attract people.
To be honest less than a month ago 20 people were beheaded next door in Libya less than half a day's drive over a weak border to get to tourist resorts so I'm surprised people aren't more weary.
Tunisia is cheap, hot and has nice beaches. You can get that anywhere in Southern Europe. So it's perfectly understandable if people switch. Sharm (long overdue a terrorist attack - which will be launched from the sea) suffered a bit with the Arab Spring. When Sharm is attacked I'd imagine tourist numbers would fall significantly.