In the unlimited simultaneous access with
perpetual ownership model, the sophisticated interactive features of each platform will add so much to the usability of the books that migration would be a mistake, if it were possible.
As I'll explain in detail later, an endowment would be one way to help guarantee
perpetual access to books even if libraries paid per - use fees (yes, the ideal
model from a strict library perspective would be full
ownership or, better yet, no limits on use whatsoever — with rights holders paid in advance for removal of all sharing restrictions).