I agree with your sales figures, but I think the royalty is worth more than 6X. No patent cliff, although I suppose there is some chance of another entrant down the line. If you figure that the "earnings quality" is comparable to that of the rest of Novartis, then they should be willing to buy it at 10x and it would still be accretive for them.
So I think I'm more bullish on this than you, although I'm guessing I'm less bullish on 118 and copaxone.