I have a feeling that JB and LA will be doing some serious sweet talking to Alberto Contador. JB and LA are both used to winning. Watching Contador go to another team and win multiple grand tours is not going to sit well with them. They're not dummies. I think AC will walk if he really is fed up after this Astana situation. But I don't think it will be because JB and LA don't want him.
I wouldn't be surprised to see them go after Andy and Frank Schleck if Contador walks.
Outside of Andy Schleck, there isn't anybody with near the upside as Contador for the next 5 years.