We already have normal BD. Sufficient reading speed for UHD.
What is the point of a new UHD-BD format, that is unsupported by older disc drives than 2015 according to Wikipedia?
New disc drives such as the Pioneer BD 221 (correct name?) support it. There is no recordable or RAM variant of it.
RAM was only for DVD and HD-DVD (hopefully included in the future HVD-RW).
My guess: industry paranoia about piracy.
UHD capable drives have a separate crypto chip which handles the AACS 2.0 encryption.
Quick answer by MyCE. Thanks.
I guess that the UHD-BD is physically readable by older drives, and the encryption can be loaded via software/firmware patch. Could be slower than hardware decoding, but should work.