This may be worth a read. It explains the process of contract termination and the implications.
I-resign.com - Community - Dismissal for SOSR - Some Other Substatial Reason
In summary, if you're presented with a new contract using the "SOSR" argument and fail to sign it, your employment will be terminated at the end of the notice period. It's automatic.
Can you be sure that every one of the 14000 BASSA members won't sign a new contract if it's presented? Some of them may want to keep their jobs....