I suspect that there'd be a fair trickle of previously-shipped Perfs on the used Model S market later this Fall thanks to this package.
A fair number of the early Perf buyers surely have the means to sell their S to get a new one with this package.
Incredibly smart on Tesla's part to stagger the release of this package till a few months into US/Canada production! Recall that Elon's Founder #2 Model S has had some iteration of this package since as far back as last June
(it was mentioned in many of the early media reviews when they were loaned Elon's car)
Suckers!