I believe that they have mentioned that they would be releasing the other modules over time. I also am highly interested in Curse of Strahd. I was very impressed with what was available in Storm Kings Thunder and hope for the best with Curse of Strahd, however there is one aspect that simply doesn't translate into Roll20 well... Castle Ravenloft itself. The map provided as part of the book would be completely inadequate for the tabletop, hopefully they will be able to provide a completely populated 3rd party option. Given the challenges with Curse of Strahd, I would also be very interested in rough timelines and specifically about whether or not there will be a tabletop friendly version of Castle Ravenloft.