Your 5x P/E for a long-running revenue stream is ridiculous
If it's truly long-running then I absolutely agree, particularly with long bonds trading where they are. But this is a situation where the market looks ahead a long way, and the market would very likely assume that in the long run (say 5 years) there would be other entrants.
Guess you'd have to do a probabilistic DCF analysis to figure out the real value here in a royalty scenario. My gut instinct is it will be north of 5X, but I'm not sure by how much.
(Of course from a tax perspective these royalty streams bestbelong in the hands of a tax-free institution, but you have to jump through some perhaps dubious loops to get them there).