Cosmo, in economics there's a difference between ascertaining an actual demand for something, and believing that there should be a demand. Unfortunately, I suspect that MNG currently has more pressing financial needs than building replica trucks for cars that don't go anywhere.
There's been a bit of a tendancy in some of these discussions to refer in general to equalized passenger car trucks with primary and secondary suspensions as "J&S trucks." However, only a few Maine 2' Jackson & Sharp passenger cars exist today without correct trucks; fortunately W&Q #3 is not one of these. As I recall, the MNG collection includes two Jackson & Sharp cars - the Rangeley, which still has its right trucks, and the SR&RL combine with the odd rebuilt arched roof, which does not. I believe what's left, post-Edaville "preservation," of the former B&SR baggage car now at Boothbay was built by J&S and, when seen last fall, was riding on freight car trucks. The one remaining original coach still at Edaville was built by Jackson & Sharp's successor American Car & Foundry and ran on original trucks until fairly recently; presumably they still exist.
The remaining Maine 2' passenger cars that have lost their original trucks were built either by Laconia (two at Phillips, one at Boothbay) or Billmeyer & Small (two at Portland, one at Phillips). These would have had Laconia trucks or Billmeyer & Small trucks, respectively. One of the Laconia coaches at Phillips has inherited a pair of passenger trucks from the Laconia-built B&SR coach that ran at Edaville as the "Elthea" before being burned down to the frame. I am unaware that Jackson & Sharp supplied "J&S trucks" to any other builders of 2' passenger cars. Thus, the maximum potential joint demand from other organizations for J&S trucks appears to be two pairs. Unfortunately, since these are the only correct trucks for any future replica WW&F coaches, it looks like the museum will be more or less on its own, although there's already the one spare pair in stock thanks to Allen Fisher. Whether it's "worthwhile" to make any more is really not a question of economics. But I'll bet if you can find someone willing to supply the money, it would happen sooner than later...