The article you linked is three years old, which can be a long time in an area of law that is evolving (and of course was written before the recent GSK v.Teva decision, which presumably will be the subject of an en banc petition).
Regardless of how the GSK case ends, Amarin should consider attempting to use the fact that only about 10% of Vascepa scripts are for the indication for which the generic was approved to impose a legal duty (of reasonableness) on the part the PBM to first inquire, when it proposes to substitute, what the indication is (90% will be a non-approved indication) and perhaps also, if the indication is the one for which generic is approved, whether the prescribing physician authorizes substitution. PBM's should bear some responsibility, under these circumstances, to (1) not dispense a generic that is not certified to be therapeutically equivalent for the intended indication, and (2) not cause patent infringement.
Amarin could also seek (or threaten to seek) state regulatory bodies to make a rule requiring such inquiry, in the name of both safety (nonequivalence) and good citizenship (avoiding infringement).
If you were a PBM, would you risk the courts' making a decision along the line I am arguing, creating precedent that could adversely impact your business model (increase your costs); or, would you try to settle by quietly agreeing to inquire for this one drug? or risk a state's adopting a rule that would increase your administrative burden for every skinny label generic?
Concurrently, and citing the same 90-10 percentages, Amarin should pressure Hikma to take affirmative steps (arguing a duty of reasonableness, and threatening suit) so that PBMs don't substitute when to do so would infringe patents. If you were Hikma, with 50(?) products, some of which have, or will have, a skinny label, would you risk a court's making new law that adversely impacts your business model, or would you try to quietly settle?
Both those measures, concurrently executed, would, imo, pressure both Hikma and PBMs to work out a solution to extinguish their potential liability and/or to preserve their business models.
This is not my area of legal expertise, so just a personal, non-professional opinion.