It seems that Sony will be the only producer of the new XQD memory cards that are used in the D4. At that point SanDisk has no plans to produce XQD cards and Lexar is still “evaluating this technology” (source: Cnet). The first batch of Sony XQD cards will be available in “only” 16 and 32GB sizes.
Nikon D4 video shortcomings based on the IR Q&A sessions with Nikon (they even took some questions from [NR] readers). Here is a quick video recap: