I reject the premise.
First, I think it's highly unlikely an effect can be overpowered no matter the cost . It simply doesn't make sense. If Luke is OP at 30 points, but not worth playing at 45 points, there will be a point cost between 30 and 45 points at which Luke is cost-effective.
Second, even in the event it happens (e.g., 1.0 pre-nerf cloak), FFG has not precluded errata. All FFG has done is make balance more easily (and more quickly) adjustable without issuing errata.