Thanks. 

Can anyone from Stardock support answer this question?

Also Stardock promise that anyone purchase WindowFX 4 will get a free upgrade to 5. Will this be a false promise also? I am a bit worried about this.

Wizard1956 gave you a responsible answer. In the thread he took the trouble to look up for you Island Dog stated that exact release dates aren't given. https://forums.wincustomize.com/413813/page/1/#3031007

Since you won't get an exact date on release, there's no point being being miffed about it.... It will appear when Stardock is satisfied with its perfomance on a variety of systems.

As for the free update uestion, as with other software developers, when updates involving going from 4.x to 4.y occur, they are free. When version 4.x goes to version 5 (usually because of the number or degree of updating of the software), it isn't free.

That isn't a definitive answer, but I don't work for Stardock, so... if you need more, write to Support or Sales, and they might have more by way of info for you.

Just wondering since I happen to like FX4 and 5 looks to be better.

ODNT subscribers will get WindowFX 5 when it's ready . . (or nearly ready )
Those that purchased WindowFX 4 (stand-alone) after the promotion page page went up will get 5 at the same time.

It will be released when it's ready.  The community members have answered the question really well.

Speaking for myself (not as a Stardockian) it's interesting to see how things have changed over time.  When ODNT was new betas (and late alphas) were released to the community much more often. The feedback loop was much shorter then.  Release to the community --> bug reports -> release with fixes -. repeat. 

Then the market changed.  It moved from hobbyists to "consumers".  They didn't want something cool that might be buggy and require tweaking . . they wanted things that just worked.  And I think Stardock had to modify how it did things because  . . well . . that was the market.

Giving hard dates is a bad thing now because people get really upset when you miss them.  But they also get really upset when you release on time a product with bugs.  -sigh-
Anyone here that has made a skin or gadget knows that things oftentimes take longer than expected.  Imagine releasing something that might be purchased (or has been purchased) by the just the four million or so members of this site?  It's better to be safe than sorry when it comes to releases.

So . . Stardock hat on:  There is no release date set at this time.  All offers will be honored.  It will be cool.