What leads you to speculate this?
If anything I would think HK would stop importing the more specialized models (Elite and Expert) before they would scrap the USP and USPc.
I think the HK45, P-30, P-2000/SK will take the lion's share of the HK market with the average shooter who is looking for a quality 9mm or .40 with good ergonomics and better CCW potential. The USP's have established HK's reputation for ruggedness and reliability, but size and ergonomics of the USP's drive away some sales. The newer models should sell better.
I'm guessing the Tactical, Expert and maybe the Elite will remain popular with shooters like me who want a no compromise German pistol with the O ring barrel and dual recoil springs. I think .45acp is the most popular caliber in those models, so the 9mm and .40 models may drop by the wayside.
The Elite would probably be the first of the longslides to go, with the Expert hanging on in .45acp. And like you say, there's no better platform for a suppressed pistol, which is why the Tactical will probably be around a long time.
Just my guess.