at coming up 24 years old, this airframe is worth the value of its 4 RB211 engines, so in the order of $15m, alas LL is unlikely to leave JNB under her own power, more likely on the back of a number of trucks....
Insurers generally work on a repair value of 60-70% constituting a total loss, this repair will easily exceed that, BUT it may be cheaper for BA to pay the difference themselves. Unless one of the very recently withdrawn units can be returned to service depending upon how stripped out they are.