According to Microsoft, 19H2 "will be a scoped set of features for select performance improvements, enterprise features, and quality enhancements."
"To deliver these updates in a less disruptive fashion, we will deliver this feature update in a new way, using servicing technology (like the monthly update process) for customers running the May 2019 Update who choose to update to the new release. In other words, anyone running the May 2019 Update and updating to the new release will have a far faster update experience because the update will install like a monthly update," Microsoft explains.
Put another way, this is going to be a relatively boring release, in that we should not expect any groundbreaking features. Microsoft has gone in the opposite direction with some of its previous feature updates, which have introduced things like the Game Bar, a dark theme for Explorer, a more robust Task Manager, and so forth. In contrast, we anticipate 19H2 being a relative snoozer.
Since 19H2 is less ambitious in scope, it should enjoy a smoother roll out.
"As with all our feature updates, we utilize a multifaceted quality strategy that includes automated and manual testing and leverages the Windows Insider Program to obtain user feedback and data on quality. The next update to Windows 10 will be no different," Microsoft says.
That starts today with the first preview build. As the year goes on, Microsoft will test additional additional builds in both the Fast and Slow rings. Broad availability to the public will follow sometime "later this calendar year."