I think carbon fiber may be repairable just like fiberglass - depends on the damage you're addressing but can be as simple as mixing some epoxy, soaking some weave and applying. Sand, repeat, etc. I'm far from an expert, so happy to hear from someone who's read or seen otherwise.
I believe the experience in the bicycle frame world is that you can repair CF frames where you would normally have to toss aluminum frames. I don't know what the answer is for CF tubs in automobiles - I know some manufacturers are bolting on aluminum subframes (Lamborghini with the Aventador comes to mind - see below for picture) which is one way to address the potential problem. Also given the strength of the material, the tubs may be effectively damage-proof (because other parts would break first). It wouldn't surprise me if it turns out that repairing CF tubs is labor expensive but possible, whereas currently cars with bent steel frames can sometimes be bent back into shape, sometimes cut and rewelded and sometimes scrapped. Aluminum repair can be even more difficult because by the time it's been bent there could be irreparable fatigue.
Bottom line we are very early in the carbon fiber era, but I see no reason to believe that within the next 5-10 years the expertise will have been built up to the point that car repair is even easier with CF than any other material.