Being that it's been released to the media for review purposes and many reviewers (possibly all? I'm not sure) have been required to send their samples back, I wouldn't expect any just yet. In the last 3 phones I have owned (all bought on release day or pre-ordered) the crash tests have come out within days of actual release.
My M8 is a dang tank and has really been abused in the last 2+ years w/ no case. I really can't believe how well it's held up. I even had to reach around in a muddy pond to fish it out. One X took a lot of drops and splashes too. So, I'm not too worried when it comes to HTC.