HTC might be trying to put the “open” back in “open source,” because their future devices will not have a locked bootloader. It’s not something that most consumers will care about, but the vocal Android enthusiasts sure will.
Either way, it’s a move by a significant company that is done for their most loyal and enthusiastic customers, which is sadly rare in the smartphone space. Hopefully this will begin to put the pressure on other Android OEMs (like Samsung and Motorola) do at least consider doing the same.
HTC hasn’t commented on what will happen with their current phones that are shipping with a locked bootloader. It’s possible that they, too, might be unlocked via a software update or a program that has to be run.