Apparently not, at least that seems to be the message over on the Daz forum, unless the original vendor updates them to work in DS6. A couple of the vendors have already been updating and testing theirs, and they will likely be free updates once they've cleared Daz QA from what I understand. Others might decide to create an updated DS6 version of the relevant plugin for sale but, unfortunately, there will be other plugins that will never be updated due to the original creator/vendor no longer being around.

If I remember correctly, Richard (RHaseltine) mentioned that there was a way of building your scene in DS4 using the existing plugins, and then exporting the scene to DS6, but I can't remember the steps required (I'm still getting my head around DS4, I think it'll explode if I also have to get to grips with DS6 any time soon!)

Scripts will generally work with DS6 apparently, so at least that's something.