The MS market in the US is highly fragmented and is quite sticky, so I highly doubt that BG-12 will be able to garner a 50% market share during the next 3-5 years.
There is good reason for MS patients NOT changing treatments. Will another treatment work as well? Could there be complications due to multiple successive treatment types? Could you even return to the old treatment or might it no longer work? Hence "sticky". But up to now, it was changing from one injection to another injection or worse to an infusion (Tysabri).
Will it still be "sticky" when there is a pill to take, and one that may offer the best reductions in exacerbation/progression?
IF I had MS and was doing well on Copaxone or one of the interferons and my insurance would cover BG12, I would switch in a heartbeat.
IF I had MS, was doing well on Tysabri, was JCV- and my insurance would cover BG12, I would be undecided and want more info on BG12.
IF what we know now holds, there should be massive shifting, gated by conservative neuro's.