OK, I found the info site for the vouchers:
https://www.vsl.co.at/en/Instruments/Voucher
Looks like the way to go, and I see that we are encouraged to stock up on them in advance, with the four-for-three pricing this month, as many new products will be released in 2017.
I've been spending like crazy lately (and not even Black Friday sales; mostly high-end mics and fleshing out my real-instrument woodwind collection with unusual voicings), but as the voucher sale extends beyond Christmas, I can always add more vouchers later. :-)
So, I'll go ahead and buy the first set of four vouchers now, get Historic WInds I, and then I suppose it will be clear whether Historic Winds II is a separate purchase and/or not available to buy yet. :-)
My recollection is that the site only supports euros, but I may check for other currencies due to how strong the dollar is right now.