It is my guess that many of the elabrate hairdos that are currently available may be difficult and time consuming to recreate with strand based hair and of course the processing time is an issue, and the same is true of many of the other new features. at the very least if you want more then one figure in the scene at a time you'll want some that don't tie up massive processing time as well as not needing the extra detail. I don't think it's productive to think that you'll have to throw your P4 models on the scrap heap yet.