My understanding is that DWCS5 will either have little or no support for ASP (any flavor).
The new areas of Dreamweaver will be enhanced objects and tools for using the big frameworks out there (which are typiclally PHP based) like Drupal, Joomla, and some other more universal systems. There have been a couple of video released by Adobe from some of their conventions that unveiled some of the new features in DWCS5 but nothing concrete has been announced yet.
My guess is that Dreamweaver will focus on PHP Frameworks because of a recent study showed that's what the majority of DW users wanted and Adobe's own ColdFusion.