Eh, I don't think Swift would ever have dethroned Python. What pain point would it practically solve? I don't use Python often but I don't hear folks complaining about it much.

I do, though, think Swift had/has(?) a chance to dethrone Rust in the non-garbage collected space. Rust is incredibly powerful but sometimes you don't really need that complexity, you just need something that can compile cross-platform and maintain great performance. Before now I've written Rust projects that heavily use Rc<> just so I don't have to spend forever thinking about lifetimes, when I do that I think "I wish I could just use Swift for this" sometimes.

You're right, though, that Swift remains Apple's language and they don't have a lot of interest in non-Apple uses of it (e.g. Swift SDK for Android was only released late last year). They're much happier to bend the language in weird ways to create things like SwiftUI.