Getting rid of the ability to use your old content is the worst mistake they can make for the next version of Poser. I use new AND old content all the time.

Having the ability to convert clothing on the fly to different figures as Blackhearted mentioned would be great if it is better as the shrinkwrapping method, maybe by having parameters to define how it should behave on the different bodyparts

My personal favorite addition would be to have a new animation room where the workflow is improved with new tools and improved editors