I guess I just don't get it. What part of "contract" implies anything other than "contract"? Things in the greater wide world can change overnight. Companies change their mind overnight. Jesus, had you been keeping track of the mismanagement goings on at Virgin over the last 2 years, why on earth would you take anything at face value?
You sign the contract, if you agree to what is in it, you work it, and you move on. Or stay if the opportunity presents. The terms are in the contract. As for VA employing on the 737 now, if you like the look of that, you can always apply. The grass isn't always greener.