It's possible that there could be one or two additional cities served by the Ryan wet-lease. The AirTran pilots' agreement with the company allows for the wet-lease to operated into two markets not currently served. Whether or not this actually happens remains to be seen. There have been rumors that the 737s could arrive before next June, but that is only a rumor, and many things would have to happen for this to become a reality.
Another consideration is that so far the Ryan performance has been something less than we had hoped for. Suffice it to say that there have been some reliability issues, and I would hope that unless these issues are resolved, AirTran would refrain from expanding this agreement from it's current level. Why risk damaging our reputation in other West Coast markets with spotty service that we don't control. I'm for waiting until we operate our own aircraft before going into any additional markets.
Yes I agree with M717, I don't think they will because they have been very unhappy with Ryan International servicing of those western routes. For a little more information on how AirTran is not happy with Ryan, check out the recent post about Ryan International and how a person who used to be a F/A for Ryan describes it in detail.
regarding the winglets, i think that whatever decision they make, it will apply to all of their 737s. this is only speculation, but it seems absurd to only equip half the fleet with winglets.
on a personal note, i hope they do. winglets make the 737 look so damn cool. i prefer the 737 over the a320, but will admit that the a320 looks better than a 737 without winglets. but put winglets on it, and the 737 is the hottest looking plane in the sky.