During a seminar in Tokyo, the DVD+RW Alliance announced to work on a DVD+RW dual layer media type (which means rewritable) to be available at the end of the year. The initial media write speed will be 2.4x.

For other standard, nothing seems to be currently planned beyond 16x for DVD+RW. The DVD+RW write speed should be increased over 8x (available since a few months ago) in 2006. The DVD+R DL write speed will also increase beyond the recent progression to 8x. None of the final write speed have yet been communicated.
DVD format continues to evolve even if these modifications seem to be the last ones. Indeed, in the months to come manufacturer will focus most of their R&D department on the HD - DVD and Blu - ray disc format development.