Microsoft's latest version of Window10, codename Redstone 1, version 1607, build 14390.0.rs1_release.160712-1452 was introduced with a suitably understated announcement on Friday by Insider spokesperson Dona Sarkar, who emphasized that it's not the RTM build.
The lists of improvements and known issues with this build are minuscule. We're very close to the final release.
If history is any indication, we're likely to see an RTM that isn't really a final version. At some point, Microsoft will choose a final build, and it'll be widely available to those in the Insider Program. No doubt we'll see some unofficial downloadable copies as well.
Then, instead of dribbling fixes out for the next few weeks, Microsoft will probably (although by no means certainly) save its fixes for one big Cumulative Update, to circulate on or about Aug. 2, which is the official release date.
I'm hearing that build 14390 is good enough to be an anointed RTM version, but there's enough concern about lingering problems -- and enough time -- to squeeze out a final, final RTM version.
If this is like previous times, when the real Win10 AU rolls out we won't have any official word. Instead there will be leaks from the dev team to tell us that the build has been frozen.
There's no word yet about Redstone 2, but I would expect to see Insider builds of Redstone 2 (with basically no visible changes) rolling out next month.