Judging from the median age of Early V8 Ford Barners (in the 60's), you have to believe that interest in the flathead era Fords will decline like it has for the Model T. In modern traffic, the Model T is barely safe getting to and from a parade. The Model A is still okay around town, but not on the highway.
Our flatheads can keep up with Interstate traffic and do so safely if the brakes have been upgraded. That drivability will extend their value, but we need to introduce younger people to the satisfaction of having a car for which you know what everything is and what it does, and that you can actually fix it yourself when it isn't working right. Next time you need to mess with the carb, or distributor, or whatever, get the neighbor kid to help. And then teach them how to drive it.
Modern cars are wonderfully functional and extremely reliable, but they are mostly very boring. Our early V8 Fords might not come with built in navigation systems, TV and climate control, but they are not boring!