Arctaurus 100% agree with the three options.
it comes down to command decision, airmanship, whatever you want to call it - not a matter of obeying a legal requirement.
Icarus53, agree that now it is a case of diversion planning vice alternate planning but, i'm pretty sure if you ditched an aircraft because your "airmanship" decision was to continue to the dest and you subsequently needed that 'unplanned' alternate/diversion, there would be some hefty legal ramifications.