I'm not OP, but it's boldly indicated that the book will be kept up to date and it will be up to the author to continuously provide new content on breaking changes or whatever happens to this stack in the future. $99 seems appropriate to me
A promise to keep a project up-to-date does not imply a promise to add a significant feature, such as multi-tenancy support (assuming that it's missing, that is). Re: price - $99 is pre-order price; by "regular" I referred to post-pre-order price of $199.
