I do a lot of e-Bay playing. Since it is the greatest source in the world for obsolete and used servicible parts for just about anything. Guess what folks, you can get the old style flexible spouts on e-Bay. You can buy one or one-hundred. What you have to know, is to keep you from using them, the bureaucrats and nanny-staters have decreed that they can't fit the old gas cans. However, the manufacturers have met these requirements by using the same sized cap with a different thread pitch.
The interesting thing about nanny-staters is that they think that their ideas and solutions to non-existent problems are the bestus and most perfect in the world. Unfortunately, they have never interacted with a competent engineer, or they would never have come up with the non-existent problem or idiotic solution.
Well folks, here is all you have to do: keep the old cap to the gas can and insert the new spout. Everything fits and works. All you have is an extra useless new gas can cap.
I notice that the preponderance of sites having these spouts for sale are in the president's state of Hawaii. I assume that because they are probably coming in from China.