My concern is that if HTC offers their version of an 'unlocked' bootloader, it gives devs less incentive to search for a full unlock exploit.
That's what happened with the Evo 3D. At the time of release, HTC's stance was that they were going to continue to lock down bootloaders. The devs worked furiously to come up with a root exploit, which they did (Revolutionary). Shortly after Revolutionary came out, HTC caved due to public pressure and offered a bootloader unlock procedure. But to get it, you had to get an updated HBOOT that sealed the hole that Revolutionary was exploiting.
This HTC unlock procedure was still kinda half-ass. It was confusing, and it made flashing stuff a lot more complex. People who rooted the homebrew way definitely had it better.
But it was obvious that the devs weren't going to toil for an exploit on the new HBOOT since the HTC way did allow you to achieve all root functionality, albeit in a more painful way. A few people continued to hack at the new HBOOT, but not with the fervor of someone faced with an unrootable phone.
So yeah, that's my concern with this new phone. I'd prefer a real unlock, not HTC's. But will we get the dev interest needed for a quick crack?