Not sure if Hot Rod's loss of our own McG was symptom of decline, a trigger of decline or both. Growing up in the far-flung frozen reaches of the Canadian north, we all (hey, it was a small town) read Car Craft, Hot Rod and PHR. I think the last time I picked any of them up, it was on McG's recommendation as it had a (reasonably) in-depth article on a topic I was specifically interested in - perhaps the junkyard 4.8 LS they tried unsuccessfully to blow up with turbocharging and made shocking amounts of power. But I digress.
Restomod to me has always meant stock sheetmetal, modern suspension, more tire, modern braking and a ton of power. Sort of taking the best of our current accessible technology and fitting it into an a classic musclecar (or truck) while maintaining the original style. Something that could be done by a reasonably capable mechanic at home, with bought parts.
Pro-Touring always suggested to me the outer limits. Not something the average mechanic has the skills, insight or knowledge to design, fabricate and build. Built by a team of professionals. Basically a race car with A/C.
What I find most interesting is how power levels that were previously impressive are showroom w/ warranty now. 300 (plus) horsepower V6 minivans for your school run. The Corvettes, Camaros and Mustangs of the day when I was a teen hovered around the 180 hp mark (not that we were ever impressed by those numbers). Now, 4-digit power levels are almost child's play and very easily attainable. Turbos and EFI to the rescue.