Um, your Super Ikonta is a nice camera, but it is not an SLR.
The more modern Fuji folding cameras are not SLRs either. Folding cameras were once very popular indeed, but none of those were SLRs.
The magic of the SX-70 design was not that it folds up (heck, even the original Polaroid 95 was a folding camera), but that it was the first folding single-lens reflex camera.
The closest thing to a folding production SLR before that was the Graflex family, but those aren't really folding cameras, since the mirror box doesn't collapse. The only "folding" aspect to those is the bellows and focusing track similar to a folding camera, but the lens can only retract a bit past infinity. Also, the big folding "chimney" viewing shield on most models gives it a "folding camera" look, but that's just a sun shield over the waist-level finder. Anyway, as far as I know, the only folding SLR ever made that was not an SX-70 or one of its decendants was also a Polaroid product-- the Polaroid Craptiva. ...I mean Captiva. I never did understand the logic behind going through the trouble to create a whole new folding SLR design around that model, given that it had a rather slow lens and had only a very limited two-zone AF system (and no manual overrride), and no close-focus capability aside from a rarely-seen closeup accessory.