The rumor from Anton's site is that V4 will be a new mesh with all new features and no planned backwards compatibility (similar to the conversion from V2 to V3).  As much as people are saying that they don't want a new figure, I'm certainly expecting that V4 will be a natural evolution forward.  In addition, the V3 market is so congested.  The introduction of a new DAZ female will bring about a new sense of competition and change some of the balance in the market place...