As of this morning the H&K USC has been removed from the dealer price sheet, a followup confirmed with H&K that it is discontinued. As of this post date, it is still listed on the website. H&K has not confirmed yet if the weapon was discontinued in Germany, or is just no longer imported by H&K USA.
Introduced in 1994 as a “sporting” weapon in an unassuming gray color, it was later replaced with an all black version in 2007. The sub-carbines are sought after by enthusiasts looking to convert them into UMP replicas, complete with short barrel. There are several businesses that are centered on making and selling conversion parts as well as gunsmithing services of these firearms.