Within the time frame you’re considering, aggregate FoB penetration of 35-40% is not unreasonable, IMO.
You and I disagree (which is fine). I believe that without a substantial incentive to force the point-of-decision decision makers to switch (e.g. monetary incentives and laws to allow the pharmacist to over-rule the MD or efficacy benefits to show the prescribing MD, ...) I don't see how you get much above what is being experienced in EU.
But I do agree that this is a good answer to my question of why the big generic makers aren't beating a path to Momenta's door.
PS Some numbers - if you assume that the non-subs take even 30% of the market then Momenta's generic gets 35% of the existing market (1/2 of the 70% remaining after biosimilars take 30%) with a degradation in price of, say, 30% - then all told Momenta's generic would get 25% of the existing market and Momenta gets about 12%. A billion or two even if Momenta attacks only 1/2 the available opportunities in 2017 or so.