The thing is that if DAZ creates a new figure, the old ones are still there.  Sure, a lot of people might want to update, since that seems to be the way things work, but some are fine just working with the last generation. It is a question on whether the benefits will outweigh the cons.

To be honest, I am not a big fan of DS and I am not a big fan of V4 (Though I do like M4) but I do see splits happening.

Poser tried a new joint system in the latest iteration but I know it wasn't very well received.

I do think the two companies need to talk more (which has been happening to some degree) so there is hope.