As I keep saying, in negotiations there is an opening position and there are negotiations to be had. Your negotiating position is no,no,no to anything, the worst case scenario is the only possibility. This is simply not sustainable.
Yes, those in the transport industry do need have to have a degree of flexibility - running the service has to be a priority and the pay needs to reflect that. Transport undertakings need commitment and compulsory flexibility - to what level and at what cost needs to be negotiated - clearly the employers are going to start from the best case scenario (for them).
Of course rail staff want to the current arrangements to continue - no problem to them if services don't run but staff sitting about (because the times don't match and flexibility is voluntary, quite apart from the ridiculous Sunday situation) - that is the employers problem for not having large quantities of spare staff sitting about for every scenario. Not sustainable for the industry : start talking the language that the employers want - cost up the options (the best case scenario for the employees) and negotiate. I expect that this will take a few rounds, but a start is needed.