Generally speaking, slow sales equates to automakers ending a particular model, usually at the end of the product cycle. A couple of signs that point to the inevitable are the lack of updates while their brethren receive regular ones, and the lack of advertising, which those dollars are allocated towards new and refreshed products. In this particular case, according to Autoblog, the Nissan Xterra may be facing the same fate as the entire Suzuki lineup, which is still subject to recalls.
There are a few things that are already working against the Xterra. Originally designed as a true sport utility vehicle, which will sport a body-on-frame chassis, its chief competitor is the Jeep Wrangler, which has been consistently been a bestseller for years now, especially since they decided to introduce one with four doors. In addition, there was a slightly larger (now much larger, and on an unibody frame) SUV called the Pathfinder, which as far more brand equity in consumers' eyes. Coupled with the increasing demand for the best fuel economy possible, more and more buyers have traded in the traditional look and feel of the Xterra, for taller wagons such as the aforementioned Pathfinder, as well as the Rogue and other vehicles outside of Nissan's lineup.
Speaking of fuel economy, the Xterra will net around 16 miles per gallon on a good day, which is no longer class-competitive. Also, since the SUV is built for American customers only, that makes it a harder business case for Nissan to justify continuing to build the vehicle, especially since only 17,000 were sold last year. Will one of the last true sport utility vehicles live on to see either a refresh, or an all-out redesign? Only time will tell, but thus far, things aren't looking that good...