This article from Digitimes breaks down the challenges DisplayPort faces and what (few) benefits it offers. Unlike DVI/HDMI/UDI, it isn't backwards compatible with anything. If you replace your PC, DVD player TV or monitor with a DisplayPort device you'll have to replace anything connected to it. It also has it's own content protection scheme, much like HDCP, but once again not compatible.
We don't really see this standard taking off with no backwards compatibility (however this release from Dell/HP/Lenovo indicates it is "possible" to have legacy compatibility with DVI 1.0) and both high definition DVD formats using a different copy protection format. With its only apparent advantage being a lack of licensing fees, is there a space for DisplayPort?