Question about dual-layer Drives/Media and rewritability

This is just a hypothetical question, since I know that there are no DVD+-RW DL type media as yet, but I'll ask anyway.

Hypothetically, if there were media of this type, would the burner drive itself have to have support specifically for rewritability on DL format encoded into the firmware? Or would the fact that the drive has Rewrite capability for single layer media cover the DL anyway? Just a interesting question, trying to understand how everything works.

Better yet, let me ask like this.... If there were rewritable DL media out now, could a typical DVD DL burner burn to it? Maybe that makes a little more sense in what I am trying to ask. Anyway, thxs!!