So I wonder what upfront costs there is for an airline to join....I assume there are some fees that you have to pay to get in, re work your frequent flier programs to fit the ST model, re-fit your software to be able to communicate with the ST reservation and airline systems, re-figure your schedule to make the code-sharing possible, add/subtract flights to each others ST hubs, and all the training of the staff....

Not a small or cheap task! Ultimately likely a good thing for all involved but....