Marty, I won't argue with your assessment that there is a lot of interest in the newer trains with the latest features and sound. But that doesn't necessarily equate to the postwar market being dead. Anymore than 027 track being dead just because it isn't currently being manufactured. The amounts of that track that have been made over the decades is staggering. Many are still using it. Once you have the layout built, your track needs tend to disappear.
Postwar Lionel trains were produced in the tens and hundreds of thousands depending on the product type. Some are reported to have been made near a million. On the other hand, the new high end trains are produced in runs of a few thousand. According to Lionel, 3,000 pieces is an exceptionally large production run of a scale Legacy locomotive. And the other companies like MTH and 3rd Rail produce runs of a few hundred... and less. I sometimes wonder how they can stay in business with such low runs.
Even with the new BTO model at Lionel, we're seeing dealers who have ordered extras and are having to mark them down (maybe at a loss) to sell them. I would suppose those dealers will eventually readjust their ordering numbers, if they aren't selling the product at a profit: Which we all know is a small figure for dealers.
As mentioned above, many postwar collectors are passing away. Others are moving away from traditionally sized trains to scale. So there is a glut of product coming to the market with not enough buyers.
I've also seen beat up postwar pieces at prices that are unrealistic. Those sellers go home carrying everything back. But when the postwar (and for that matter, product from other era's) products are reasonably priced, they're still selling. If I buy a postwar or MPC car for $10-15... I can't buy a pair of new die-cast trucks for much less. Even a pair of plastic trucks will run $10 from a parts dealer.
I guess it depends too on regional markets. In the shops I've been too, I seldom see expensive scale products on the shelf. Those dealers tell me when they stock them, they end up losing money on them. They'll happily order the products, but won't just stock them without confirmed orders.
The whole market is changing. It is more diverse than ever, and regardless of new interest, I suspect is overall smaller now than only a decade or two ago. And Lionel is in a tough position of trying to appease the adult operator, while at the same time reaching out to the next generation with affordable product.