Exactly like the rolling development model used to make openSUSE Leap 42.3, Leap 15.0 will use the same model until its final build. No concrete milestones will be used building up to the final release, which is expected in late Spring. As bugs are fixed and new packages introduced or excluded, snapshots of the latest beta phase builds will be released once they pass openQA testing; the first beta version build (Build 109.3) of openSUSE Leap 15 was recently released and there are currently two follow-on beta builds that would feature minor improvements if the beta builds pass openQA .
Also: KDE Plasma 5.12, Btrfs Improvement, Linux Support for Wacom SmartPad Devices and More