I think a important feature for the next big disc encryption application would be to provide support for modern input devices a.k.a. touch screens and a on screen keyboard (OSK).
Many modern devices a.k.a. tablets don't have an physical keyboard anymore those making entering a boot password there as inconvenient as possible.
For my old viliv S5 umps i modded disccryptor to have a arrow +enter key based OSK, but this device head a few keys at least.
modern tablets have 1 win button + 2 volume buttons, or not even that.
Adding here a key based OSK would be if not impossible still mighty inconvenient.
So there is no really good way around adding some kind of proper HID device support.
on a side note the very well hated bitlocker does not have such a feature, so if we would have it it would be a really good advertisement point.