Quick answer -- it will continue to operate, although not as smoothly and with greater stress on the other parts. By all means use it to get back, but replace it right away before you break something else.
The Drive will operate in some fashion with a wide assortment of failed parts. My friend threw a fin the other day and pedaled his Revo 13 back at about 3.5 MPH with his remaining one fin. The Drive will also operate with the failure of any one of the three cables. Users who don't know this sometimes do a lot of unnecessary paddling!
