i doubt they'll throw out the $10 tix. these $10 tix get sx more exposure than they could ever afford to pay for thru advertising. they're a great marketing tool. the question is this: what's the opportunity cost of a $10 ticket? in the case of sx, the opportunity cost may even be negative - if the holder of a $10 ticket wouldn't have otherwise travelled at all, then if nothing else, he/she is a generator of ancillary revenue. in the case of a full flight, the $10 ticket may have a more significant opportunity cost - but, for the most part, i doubt sx loads are above the 70-80% range (many flights to FL may be an exception, but i imagine these flights are cash positive, $10 tix or not).

therein lies the fundamental problem w/ the airline industry as a whole (less of a problem for sx, but a major problem for all other airlines): the marginal cost of flying another passenger is 0. at the end of the day, if an airline still has empty seats, there's a nearly irresistable temptation to sell those seats at almost any price, however low (as long as the price covers the transaction cost of selling the ticket).

In the case of sx, that transaction cost is the lowest in the industry (well under $1) due to 100% internet distribution for tix sales. more importantly, every seat occupant has the potential to generate ancillary revenue (the breakfast bagel sandwich isn't bad (really!) and you need a ginger ale to wash it down). thus, if the $10 tix holder would have likely not otherwise travelled for a higher price, and there are open seats anyway, it's worth carrying him along for both ancillary revenue and major PR exposure.

unless the entire business model changes (i doubt it will), i think $10 tix are here to stay, in one form or another. btw, one of the most successful carriers in the world, ryanair, still does it.