This is a very interesting development and I'm curious to see what comes of this. I think it's quite an exciting possibility.
But the article shown is mostly based on speculation and educated guesses toward Amazon's business model. We all just have to wait and see what Amazon's plans are when full details are eventually released. While this is a potentially neat service, my own interest in it from a consumer standpoint is dependent on what authors and titles are included and what impact, if any, it has on the Prime membership.
TechCrunch speculates that it would be "presumably untethered from Amazon Prime," but without any official word from Amazon it's hard to say. With the recent price increase in Prime and already having their toes in the water with the Kindle Lending Library, I'm hoping that Kindle Unlimited could act as both a standalone subscription service for those who want it, while also serving as an additional incentive for current Prime members with Kindles/Kindle apps. The TechCrunch article is based off a cached link, and there's no current info available on Amazon, and it seems like all the links are dead-ends.
I'll wait for more details to come out, but I'm cautiously optimistic.