it is extremely unlikely we will see any major hardware updates at WWDC. WWDC is for developers... and i don't think a software developer is really all that concerned with an ipod after paying 2000 dollars to attend. maybe a new technology that would open up new doors for developers but doubtful on new products. also as some one else here has said, its never been done in previous years. so i would say no your probably best just getting it now, after all you can start enjoying it sooner.
maybe at paris expo or macworld boston
as far as the volume concern, there are many many hacks out there to remove the volume limiter so that really isn't a problem.
enjoy your future ipod love affair