While I personally never uses V4 (only for doing tests) , she will stay for some years to come. Probably at least one or two decades more, probably longer.

Why?

Most end users are way over their head in V4 content investment.

And be honest? Is there a worthy alternative?

My Michelle? Dawn? Antonia? The Genesis series?

All combined and taken to the square, they do not have 1/100 of the V4 content available.

And what is even more serious.
The content market is saturated right now.
There is no gap to fill with a new figure and start all over again.

A new figure only has a chance to survive when she comes with the next generation of Poser users. The current onces depleted their wallets on V4.

That is the "WHY".

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!