You are welcome. I am confident of that the future discs work exactly as I described. UV is a different organization from Blu-ray Association and has no ability to change that specification. It is a "layered" solution on top of BD offer; in this case, it is the addition of streaming/download rights to the same disc. So you can completely rely on such discs to be compatible with BD players of any type. The BD player never sees anything related to UV.
So while the UV offer may change in the future as the standard evolves, the trigger for it, the BD disc, remains unchanged.
All of this is motivated by the fact that BD is born in an era where computing devices are moving away from having optical drives. Tablets, phones, and small form factor notebooks do not have the mechanism to play the discs so other solutions had to be invented. Initially it was to release secondary copies of disc on extra DVDs that held the DRM protected versions of the file for PC and Mac. Now they are trying to move in this direction to allow online access. Lack of "portable" playback has been thought to be a hindrance for BD adoption and this is the way it is being resolved (or hoped to