You know, this kind of surprised me, but I can't think of anything that hasn't evolved for the better:

Boy Scout Pocketknife ==> Leatherman Charge Ti
Buck Special ==> Becker BK10 & Benchmade Rant
Aluminum Canteen ==> Nalgene Widemouth Bottle
Zippo ==> Bic & Spark-Lite
Aluminum Canoe ==> Fiberglass & Composite Canoe
Film Camera ==> Digtal Camera
Incandescent Flashlights ==> LED Flashlights
Regular Batteries ==> Alkaline Batteries
Canvas Backpack ==> Cordura Backpack
Canvas Tent ==> Nylon/Polyester Tent
Canvas Tarps ==> Nylon Tarps
Down Sleeping Bag ==> Polyfill Sleeping Bag
Open Cell Foam Pad ==> Thermarest Pad
Cotten Clothing ==> Synthetic Clothing
Metal Mess Kit ==> Lexan Mess Kit
Metal Utensils ==> Lexan Utensils
Regular Paper ==> Write In The Rain Paper
Windup Watches ==> Digital Electronic Watches

Even dental floss has improved a lot

A few things that haven't changed much:
Silva-type compasses
Binoculars
Toothpaste <img src="/images/graemlins/smile.gif" alt="" />
Pencils
Remington 870 Shotgun
Water