I am sure that these cars would be spectacular in detail, features, and price. The scale modelers should be accustomed to all three when investing in brass models, and it is surprising that they are not elated that a manufacturer has expressed interest in giving them what they have continued to demand and while they continue to rail against American Models, Lionel, and MTH for not doing the same. 3rd Rail has to determine where the interest lies in order to commit to manufacturing, and those interests are divided among prototypical scale or high-rail wheels and prototypical lengths or shorter versions to manage tighter curves common to high-rail. Those interests are further divided among all the desirable road names. You can divide a pie only so much before it becomes pudding.
The news is thrilling to me, but the requirement of buying 6 to 8 cars at once is substantial. I suspect it will be the same for many others. Perhaps a more realistic approach is to offer a choice of coach, diner, and baggage rather than a full line-up baggage/mail/combine/diner/ dome/coach/ two sleepers/observation that would put the total cost over the top for many of us. Coach/diner/baggage or some such combination of full-length cars could "blend in" with the American Models cars many of us already have. Choosing road names is also a stumbling block for getting volume; but the existence of American Models' Pacifics, PAs, and E8s and others as Bob Bubeck mentioned is a clue as to what locomotives can head these new passenger cars and likely what road names of passenger cars the aluminum ones can complement. Cross-country through cars often meant "blended" road names such as New York Central with a Santa Fe sleeper.
My fear is that too many different requests (full or short length, scale or high-rail wheels, road names) and too high a cost for a full 8-car set will be so restrictive that 3rd Rail will not find enough consensus to go ahead. If those of us in 1/64 scale could combine our pent-up buying power to fewer versions with the chief option of scale or high-rail wheels, 3rd Rail might be encouraged by the volume. It would also mean less risk for the manufacturer. My personal choice would be 3 cars of Santa Fe Super Chief/full-length/scale couplers/high-rail wheels; but I would be willing to go along with the crowd to get any 3 high detailed cars. I just hope we can get a "crowd" together!