Value seems unaffected so far - can still be found new on gunbroker for $450 to $500 or so.
It is true they stopped importing the GSG-5. However.....they are now importing the GSG-522, which is the post lawsuit model..which has a few mainly cosmetic differences but internals are the same. Apparently, they will also be bringing out parts kits to make them look exactly the same as the GSG-5, which is apparently ok via the lawsuit....what a pointless exercise that was by HK.
Because of this reimporting of a new model, I doubt the 'original' GSG-5's will gain much in value, at least in the short term. Another factor that is keeping the prices down are the quality competitor rifles based on the AR platform that are now out, such as the S&W M&P 15-22's.