There is no immediate plan to introduce a 6" sanding disc.
However, a customer who also had a 6" ROS, recently told us that they purchased a cheap 5" random orbital sander at a garage sale and used it for the 5" carbide discs. They said the advantage of the long life of our carbide sanding disc, more than compensated for the 1/2" less abrasive on each side of the disc.
Please note the vacuum hole pattern is compatible with most 5" diameter sanders with a 5 or 8 vacuum hole pattern, but not Festool® orbital sanders