Apple has released .1 betas of fully unreleased software in the summer before, but this seems really, really early. If Apple is planning to internally finalize iOS 18.0 by the end of July, since betas provided to the public (dev and public betas) are a few weeks behind their internal builds, I think we will still get iOS 18.0 betas into August, although perhaps not as deep into the season. Historically, the build number from the mid August betas is often very close to the final beta any way, and again, operates on a few weeks lag from what they are using internally. Then, we will ultimately get the zero day 18.0.1 update when released to the public in September and the new iPhones arrive to customers, which will probably jump a few builds. I just don't see them fully abandoning the 18.0 beta tree when the 18.1 beta tree launches, whenever that may be.