Careful about that II comment
Those are coming into their own right, but certainly not as popular as their predecessor or the Fox-bodied variant.
I think the Fox-body may be seen more by the muscle/race car crowds as plentiful and cheap horsepower. Let's face it, that generation Mustang really did a lot to bring an aftermarket to the Mustang name, due to the "5-Oh." And, lots of engine interchangeability could be had if you wanted to build something really nasty.
The SN95s were an improvement over the Fox in many respects with the new chassis, and again, we saw a few different engine configurations available in these. Particularly with the '94-'98s. And even the New Edge, to a degree...but you certainly don't see as many big-block swaps in the SN95s as the previous generation.
Not to mention their production lifespan. You basically had 15 years worth of the Fox-bodies, and a combined 10 years of the SN95s...5 years for each '94-'98 and '99-'04. So take that into consideration as well.
When the 1994 model came out, I had just turned 16. I was in the process of getting my license so it was the first new Mustang I got to see when I started driving. I thought that thing looked so awesome...of course I wanted one! In 1999, my initial impression of them was "meh." But with a few tweaks on the '01, it looked better...in '03, I bought a new Sonic Blue GT and still have it. Still see a lot of New Edges on the road too. And unfortunately, as time wore on for the '94-'98s, I personally started thinking the design looked a little bland.
I was never crazy about the Fox-bodies though. They're just too boxy looking and about the only Mustang design cue they have in them is the long hood/short deck proportions. No horse on the grille (save for the '93 Cobra), no side scallops, and the tri-element taillights are mostly non-existent. In my opinion, I feel the Fox (at least in appearance) is less of a Mustang than the Mustang II.
I can't say what the future holds for the early SN95s. But hopefully people don't forget them, or any part of the Mustang history, and keep up on them with some fine examples. I've been to shows and certainly see some nice clean rides there from that era...so hopefully those that have them, hang on to them. We're starting to get into the timeframe that that generation can start being considered "Historic!"