We haven't seen a new beta for iOS in a month, they're withholding the builds with Force Touch APIs included to prevent leaks and will release it after the keynote.
However, Apple is really conservative about how they release new APIs. It is far more likely iOS 9 will have Force Touch APIs as a private framework for their own first-party apps and iOS 9.1 SDK will be released shortly after the public iOS 9.0 release with full public API support for third party apps to use.