True you saw that correct.
However if we can test your patience a bit than we will be able to offer you something you might not have seen yet …
or CSV-1477: http://www.club-3d.com/index.php/products/reader.en/product/usb-a-to-displayport-12-dual-monitor-4k-60hz.html
These products will work on any Host System with USB 3.0 port also MAC, and will enable you to connect 2 x 4K Screen at 60Hz to those systems !
Product are expected to become available second half of June.
Pricing should be about 100,- USD end-user without VAT for both.
This way you can use your system for years to come wihtout missing out on the new 4K screens at 60Hz 🙂