I think one of the issues for airlines will be their longstanding desire to offer the best fares by booking well ahead, and then insistence that the moment you book, you cannot get your money back. This means that when there is any uncertainty about what may happen at destination (eg the cancellation of the Geneva Motor Show, mentioned above, done with 1 weeks' notice) there are going to be a lot of business travellers with now useless plane tickets. Hotels and car rental are not nearly so bad with this. This approach is very rapidly going to put people off advance booking.