Verizon is doing this on purpose - they want to keep pushing this thing back if necessary. Most likely it has to do with the iPhone, and no matter how you feel, that is now Verizon's top moneymaker and their only ticket to winning subscribers from the other carriers.
I would think it's more likely that HTC doesn't want to get slaughtered by iPhone sales. Like no sane video game publisher releases anything around COD, Halo, or GTA.
That may be part of it too, and also Verizon's doing as well - the fact is, Android handsets are going to be slaughtered by iPhone sales on Verizon anyway.