The USP line was updated 20 years ago.
The update was called the P-Series (P2000, P30) or the HK-series (HK45, HK45C).
Seriously, the USP won't be receiving any "updates", if anything it'll be dropped from the catalog for an updated P or HK series.
I expect the P2000 series to be dropped as well when the CBP contract runs it's course.
The current HK45's are the best 45's H&K has ever made.
The P30 just needs a few tweaks to beef up the recoil spring hole in the slide and it'll be the best 9mm/40 H&K has ever produced.
I'd place money on seeing a new "HK9" and "HK40" before seeing an updated USP.