Personally feelings are that the trend generated a lot of interest because it was available to the common man with shallow pockets. Careful spending followed up by artistic assembly resulted in a rod one could be proud of.
The flip side were those who "didn't get it" and threw tons of money at the project resulting in "clown rods" with skull air intakes and V-12 tank engines.
A proper nostalgia rod is only a few thousand dollars away from being a beautiful street rod. One has to know when to stop, but few do...
Is the trend over? Doubtful. A trend that lasts this long tends to fade out slowly. Especially since building one is so easy, provided one has proper restraint.
For the trend to be totally over... there has to be one to take it's place and so far the only trend growing right now, according to the latest SEMA pics, is one tipping the scales back to big bucks. (No name for it yet but I call it another run at the phantom craze that swept the hobby back in the 80's)