Even more information: http://www.arm.com/files/downloads/ARMv8_Architecture.pdf

The answer is that there is only one 64-bit ISA, but all current 32-bit modes are still supported.

Yeah, I just found that this morning. I'm sort of leery of the move to 32 GPRs.

I would not be surprised if they made a Thumb32 to match Thumb. Its a rather useful mode for certain kinds of programming from what I've heard from coders on ARM platforms I know.