>>Returning to your example of the IFN-alpha drugs, it’s worth noting that SGP’s archaic Intron-A continues to rack up annual sales in the hundreds of millions of dollars.<<
Pegasys and PegIntron have >95% market share. That of course means the non-pegylated IF-alphas have < 5% market share. Could be well below 5% market share; I'm not sure.