The A/G wagons will likely follow down the same path as wagon models of nearly every other collector car- as more time goes by, they become more and more valuable. Today it is just about impossible to find an A/G wagon in all original excellent condition. They were often abused or heavily used by their owners for chores, etc. And as they didn't have the stature for anyone to think they would ever become collectable, it makes finding good ones that aren't rusted out or modified very difficult, that with the lack of overall demand for them they are still being crushed every day.
The fact is though, underneath that sheet metal, they are every bit an A/G car as any hot rod coupe out there. They are also fun to modify if you find one in good shape, that fun being they can still be had for very little money today. I got my '81 Malibu wagon for $2200 last year on E-Bay, and it gets more attention than I honestly care for when I drive it, the most common comment, "It's been a long time since I've seen one like that."
-Mark-