It is not over yet: last week we had new betas released on separate days (1, 2), and today two more are left.
Apple has just made available to developers the macOS Sierra 10.12.4 beta 8 (build 16E192b) and the watchOS 3.2 beta 7 (14V5249a).
It is quite obvious, at this point, that all updates including iOS 10.3 and tvOS 10.2, which have not won new compilations today, are practically ready for release. But Apple still wants more tests to be done, it seems.
Even with today's releases, I wouldn't be surprised if all four operating systems are released to the general public this week.
Update · 03/21/2017 s 19:00
Today, Apple also made available to developers the Xcode 8.3 beta 5 (compilation 8E161).