Skymining,
Emma Radacanu was never #1 nor did she come close to sniffing it. Her peak rank was #10. Naomi Osaka was #1 and had #1 talent, but was #1000 mentally. She is a complete and total head case who cannot handle pressure, media or anything that most pro athletes deal with routinely. I doubt she will ever be #1 again. These two should not even be in any discussion on this issue.
Iga Swiatek stands on totally different footing. She is 21 years old, has won 3 majors, and hasn't lost a set in any of the the 3 major finals she has played. Barring major injuries, she is a generational talent, with the topsin she generates on her forehand. We are talking Martina Navritolova or Steffi Graf or Serena type generational talent. She will likely always be better on the clay courts than hard courts, so it's possible she could develop into more of a clay court Queen, but yesterday announced her arrival on hard courts.
I do see Coco Gauff as her possible long term competition. Coco is only 18 years old and 3 years behind Swiatek developmentally. But Coco eventually could challenge Swiatek, especially at the US Open and Wimbledon. I was disappointed with Coco in her loss in the QF to Caroline Garcia. I expected that match to be more competitive and Coco to win. So she still has work and maturation to do. Maybe we expect too much from her, but she is only 18. Coco has an edge on Iga athletically and in her power potential but even with that, Iga's topspin will make her a big challenge.
I should also note that the way Iga hits her forehand may put stress on her wrist and elbow over time. Just like Tiger Woods' golf swing put stress on his lower legs, causing him to change it. So we will need to see how healthy she can remain over time.