I joined the group buy as well. I have tried many sample libraries and hardware solutions recently and though I feel PTQ is still missing something in the way of tone, it is still the most playable piano I have come across. As such, my search is over and I'll be very happy with it for a long time to come. I won't be looking at any new sample libraries for quite a while.
As for pricing and the future (just speculating and rambling):
Regardless of the unique versatility and playability of Pianoteq, it is still competing against an ever-increasing crowd of substituting products in the form of sample libraries.
The current (normal) price is right up there with the top sample libraries (around the $400 mark with the dollar being what it is these days) and though I wouldn't know, I am not sure that this is the best price point.
Competition from hybrid products as well as entirely modelled products is also likely to increase. PTQ being proof of concept (though there is still room for improvement), others are more likely to try their hand at doing their own modelled piano (not sure what patents ModArtt or GEM have to prevent this).
My guess is that the competition will keep a lid on the price, even on the top version of PTQ, whatever it might be. I also suspect that we are going to see it split from the "one product, one price" model into multiple versions with various restrictions, as well as more bundle offers (like the one from Korg).
I also hope that the speed with which this group buy was filled will suggest to the company that the price for the current product should be lowered a bit, and then offer a "Pro" version with access to more of the internal parameters (or whatever) at the current price point. A product at a higher price is unlikely to sell in vast quantities.
In short: I'm not worried. And even when (not if, but when) a substantially better product (PTQ or otherwise) comes out, the cost of paying for a new, full license (if it comes to that) is neglible compared to having to replace a digital piano. I would rather pay $300-$400 every 5 years to replace a piece of software than $2000 to replace a digital stage piano. Come to think of it: In a couple of years, things have improved to the point that I do not expect I am going to need to upgrade anything at all.
So the Roland RD700GX just came out and now it has a sampled piano with - what? - 4 layers? Are we going to wait another 5 years and see a new version with 5 layers? Or are the hardware people going to see the light and follow in GEM's footsteps?
I would like to see something like PTQ built into a stage piano or a hardware module. I suppose a Korg Oasys (Linux?) could do it today or one of the VST boxes, but those are pricey solutions compared to using an old notebook or PC.
Would be interesting to know if ModArtt is working with any of the big guns to have the technology (concepts and algorithms translated to another platform) built into a sub-$2000 piano, but we are sure to be the last to know. Also, I'm not sure how a marketing department would feel about not being able to say "we sampled the finest European grand piano ..."