htc has said they will allow all modles to be unlockable,unless carrier restrictions apply.
verizon and ATT have been nororious for trying to keep their high end devices from being unlockable. early on,phones were able to be tricked into unlocking with a change of CID,but write protections of the memory blocks where the CID lives now prevent that option.
having said that,ive not known of any t mobile or sprint devices to not be supported,so it should remail easy to unlock those versions,even if ATT pulls the plug on theirs.
the "this is permanent" statement is likely refering to the fact that a watermark will always remain,to alert those who look,that you have unlocked at one time. the bootloader is re-lockable,but at that point,you are relocked
and not locked
. if s off is achieved,then even this watermark is reversable.
its extremely easy to root any device that provides access to boot,system,and recovery. the hard part is gaining that access. pre-htcdev some sort of exploit needed to be found. with htcdev,you just go to their website and unlock
the basic steps to root ANY htc device with an unlockable bootloader are:
-flash root files with recovery