My company that I work at actually closes bug reports that has been in "pending customer feedback" for more than 6 months automatically. The customer is free to re-open the issue at a later date if it's still an issue.

I personally think that's fine. You'd have the time to verify and close every issue in a perfect world, but the world rarely is. Before that we had 100+ issues open with bugs we could not even reproduce that where open for years. It just becomes clutter at that point.