I have read about all the Salkinds' ideas. But that is what they were, just ideas. Christopher Reeve was always going to be there first choice for any new Superman movie. Only if he turned them down would they have moved on to someone else. It never got to the point of being ready to go into production. The Salkinds reputation was damaged tremendously with their 1992 Christopher Columbus movie. Its an impossible to know What-If, but if Christopher Reeve never had his accident would he have done another Superman movie? I think so. Sure he would have been older, but he would have been much younger than some of the older actors returning to iconic roles we have seen in recent years. We likely would have gotten a film a lot sooner than Superman Returns, probably a "Death of Superman" adaptation without all the baggage of having to reinvent the character that prevented all the various attempts during the 90s.
Following the Death of Superman comic, Wizard Magazine had a special issue about Superman. There was a section on the history of tv shows and movies. Plus potential future ones. I was 12 when I bought it. It was hard for me to wrap my mind around the idea of there maybe being a new Superman movie plus maybe Superboy tv movies plus the first mention I remember about a show focusing on on the private lives of Lois Lane and Clark Kent. I assumed all these things would happen but of course only Lois & Clark did.
Oh and in that article it mentioned that Perry White would be played by a black actor in L&C. A recent book about Superman's history revealed that was producer Deborah Joy Levine's original intention. She wanted to cast James Earl Jones as Perry. He had expressed interest in the offer but DC Comics thought it was going against tradition. Of course Jones did finally appear on the show in a guest role as the new owner of the Daily Planet, Franklin Stern. Shows how much times have changed, now Lawrence Fishburne is playing Perry White.