I know that the cost of properly assessing the wing can't be ignored but it looks to me as if the only repairs needed will be to the outer end of the wing, and not substantial even at that - probably not that costly even given the age of the aircraft, if it was intended to fly for another few years otherwise.
Depends on whether the front spar is damaged, whether the technical know how to repair is available locally and whether the parts required for repair are available.
Either way, hope those involved have a fair investigation and that BA can demonstrate true colours in support of just culture if this has been an honest mistake, despite its cost. We don't get to pick how expensive our slips errors and lapses are at the end of the day!