Dell will completely switch to Display port on all of its notebooks. It plans to do this for its monitors at the same time. The strategy is simple, this will happen in 2008 and as Dell makes and sells monitors it will simply force users with to go for the new display.
The prices of the displays are really cheap and Dell hopes to get people to upgrade as well. You can tell even today that 2008 is the year of Display port and Nvidia and AMD are about to announce their Display Port cards.
The fist Dell Display port only notebooks will come in early 2008 and the display should follow.