It has little future, but to say it's dead today? Not quite. The adapter works well for what it is, and the $80 for the adapter can be cheaper to implement than a new multi-bay enclosure. Gigabit will be supplanted by 10G within two years, but there'll still be a need for it, and the same can be said for eSATA.
I'd love for everybody to have the money for multi bay Thunderbolt enclosures. Until the price comes down on them, though, we'll have adapters like this.
Plus, this adapter gives USB 3.0 to 2011 Macs that have USB 2.0 onboard.