It's worth mentioning the possibility that these "iPhone" parts aren't legitimate. iResQ hasn't revealed its source for the part, and purported iPhone bezels leaked in 2009 turned out to be parts for a completely different device. The backside of the supposed next-gen iPhone's face is missing quite a few parts present on the iPhone 3G and iPhone 3GS, which either means the part iResQ received was incomplete, the next-gen iPhone has had its internal hardware shifted around, or the part is fake.
So case manufacturers, don't throw out your old blueprints just yet. Unfortunately, it's likely we won't find out whether these are legit or not until June/July of this year; despite rumors of an iPhone update in April, the most likely date for the next-gen iPhone's release is early summer.