Pentagon was one of the first synths that I purchased.  I would definitely be interested in seeing an update.  Maybe that's the special surprise listed on the Upcoming Features page.
 
In no particular order here are the features I would like to see:
1. A new preset system. The clunky .fxb system from 2001 needs to go, to be replaced with something which allows you to have some degree of patch organization.

2. Allow import of wave files in the way Rapture does. I'd like to run some of the Architecture waves through it.

3. Redo the effects system. I dig that Pentagon has this total 79-82 vibe to it. I'd like the effects to reflect that too, by including options that someone might have used during that era. For example:

• Phaser that sounds like Small Stone.
• Flangers that had a real swoosh to them.
• Ensemble effect taken from string synths of the period
• Distortions modeled after Big Muff or Rat
• Delay with Tape/BBD/Digital options, with multiple resolutions for the digital delay.

4. Nobody would complain if the oscillators sounded a little bit better.

FWIW, Pentagon was dropped from SONAR. It was last bundled with X3.

They also kept Square I.  I wonder why they would do that?

Well a version III of PSYN would be most welcome; beef that motherfuka up and deck it out with a big palette of lovely new presets relevant to modern EDM-Pop. If Cakewalk have dropped Pentagon i am sorely disappointed and demand they bring it back now and give us a version II.
Z3TA+ DOES NOT USURP OR REPLACE PENTAGON! Are you hearing me Cakewalk? Pentagon is a beast in its own right, bring it back now!!! Give it a tune-up with some refinements to the synth-engine etc and add some better presets then update the graphics faceplate and eq section and bang! We're back in action for the brave new world. I'm weeping and wailing and lamenting and howling right now over the loss of Pentagon, and especially because that might preclude any update thereof.

Time for an Octagon.

Pentagon was one of those synths that got so hosed on a DAW rebuild that in every instance it crashed out and had to be replaced, but wouldn't retain any of its patch info. Totes frustrating. Shame too, it's actually quite a powerful synth.
 

Drone7
Well a version III of PSYN would be most welcome; beef that motherfuka up and deck it out with a big palette of lovely new presets relevant to modern EDM-Pop.

PSYN originally came out with Project 5.  PSYN II came out with Project 5 v2.  That history does not bode well for a new release of PSYN.