Poser 4 hit the classic sweet spot. Earlier versions like the first Macintosh, the Wright brothers first aircraft, etc. were great new things but they took a few iterations to become really polished. P4 is a classic and I think that's why it's lasted so long. It has enough capability, low enough hardware requirements, and a reasonable learning curve that it is still a truly useful application. It doesn't have features that some people now feel are must haves, but it must have everything that some people really need/want or they wouldn't still be selling it. I doubt that any current or future version of Poser will have the life that Poser 4 has. Like a classic 60's muscle car, the Swingline stapler or any number of iconic products, Poser 4 may be improved on but never really equalled.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken