It’s looking like the final public version of Fire OS 5 for the 1st generation Fire TV and Fire TV Stick will be released very soon. Amazon has just updated their Fire TV Source Code Notice page with the partial source for the upcoming Fire OS 5 software update. The page lists that the Fire TV Stick will be receiving an update to software version 22.214.171.124_user_20150925, while the 2nd-gen Fire TV will be receiving a launch day update to software version 126.96.36.199_user_20150922.
The update for the 1st-gen Fire TV is not yet listed on the page, but don’t read into it too much. Amazon has always been pretty bad with keeping the Fire TV’s source code notice page up to date. For example, they don’t even have the last 4 Fire TV updates (188.8.131.52 thru 184.108.40.206) listed on the page. It has been fairly common (but not definite) for a new software update to begin rolling out to devices within a couple days of it appearing on the source code notice page.