In the absence of official release dates we often rely on retailer listings to get an idea of when a particular title is launching, and while many of these are usually incorrect guesses, Amazon - by and large - gets things right most of the time.
That's why we're willing to believe that a recent listing for Project Octopath Traveler on Amazon's German site is legit. The retailer has the game scheduled for launch on 17th August this year, which is a Friday - the day that Nintendo-published games traditionally launch on.
We certainly can't say for sure that this is correct, but given the length of time the title has been in development, it would make sense in terms of timing. The game doesn't have a final title as yet, so we'd imagine that we'll be hearing more about it in the not-too-distant future - in an upcoming (and long overdue) Nintendo Direct, we would imagine.