Any of the true 'outdoor nature' sets can certainly be used with any time-themed era. The Hinterland series of Cliffs, Caves, Forest, etc. - or any of the older CaveWorks, Skull Island, WildWoods, etc. as well - are suitable for any period of any genre. Desert ground tiles can be found in Mars Station, Deadfall, as well as sandy soil in Atlantis and Arena Works.
The problem, of course, comes in when you work in the Human Factor (this goes for Dwarves and Elves as well). Architecture, in general, becomes specific not only to genre, but period and locale as well. Also, the flavor of the campaign somes into play: does the 'future' have the look of a nice clean ship as in the Star Trek Federation, or a grungy ship such as is found in Star Wars?
Some styles can cross between a couple of themes - such as Mayhem serving not only as current modern (possibly even slightly retro, a la pulp) but post apocalypse as well. Basic medieval stonework can serve as a broad base for many themes because everyone uses stone at some point in their cultural development!
But any culture will (eventually) put their 'fingerprint' on the styling of their buildings - which will in itself change over the hundreds (or thousands) of years the civilization exists. This is what WWG is so good at: the imagining of the diversity of those worlds, building on the uniqueness of those civilizations so the players can more easily immerse themselves.
There can not be 'Only One' scenic style - not even 2 or three - simply because of inherent cultural variety.
I do understand your call for maximizing multiple-use of sets. Really, I do. In answer, I refer you to the Himmervale sets. Good stonework of a practical 'universal' appeal. Applicable to medieval, modern, even future settings. Goth, Fantasy, Horror, SF, Steampunk - these and other genres can all be easily served by the Himmervale sets. Granted, it may have a slight 'darkness' to it and may not be suitable if you are looking, say, to run an Enchanted Camelot type campaign where everything is 'pretty'. I refer again to the earlier Star Trek/Wars comparison.
In the end, it all comes down to Flavor and personal choice for the build. Not to confuse the issue (or start an opinion war), it can summed up with the following Question: McDonald's or Wendy's - which burger do you want?
EDIT:
Um, yeah my face is a little red here - I forgot this thread was in the TCP section of the Forums as I was writing my reply, so I apologize somewhat for all the tLX references. My bad. My reasoning, however, is still relevant. And considering the long lead time obviously necessary to put a physical product like TCP into production (after the first step of designing it [which was the thrust of your original request]) and into the supply chain, it is going to be quite a long while before we would see it. Fortunately, as proven elsewhere in the Forums, TCP and TLX do play well with each other.
