The 1967 borders mean... the borders prior to the Six Day War. And those borders - the 1949 Green Line - weren't defensible. At all. So Israel will never retreat to them.
1. The 1949 Green Line was based on an armistice agreement. It did not formalise borders
2. The 1993 Oslo Accords didn't formalise borders either. That was left for subsequent negotiation... which of course, broke down.