Athearn tried a run of Model A Fords several years ago...in 1:48. A few JD tractors, too. Hard sell at the time (wrong era? wrong price? Too much of the same? Who knows?),...now they seem to get fair-to-decent secondary market prices.
As an aside....unless something has changed at the (new) GM licensing staff, they're pretty stingy with their license-to-manufacture of items that can be chewed, swallowed, choked upon, etc., etc. by unsupervised kids. Lawyers, knowing the depth of GM pockets but not the Chinese manufacturer's pockets (whatever they are in a different world of politics and litigation?) found a gold mine. GM jerked the reins, trashed the rubber stamps. So, a layout full of Fords and European/Asian cars in 1:48??? No thanks.
As this was discussed in earlier posts through the ages, the diecast automotive market has its own following that it caters to. Whether the basis for the 1:43 segment is related to the European O scale model trains calculation or not, there's a lot of inertia among car collectors to support that segment. To come up with an acceptable diversity of products in a scale only a few points off of this paradigm...at a reasonable cost/price...would seem akin to pushing a car up a hill with a rope. Not impossible.....maybe just improbable.
But, hey.....good luck scratching the itch!
KD