People used to think the same thing about Objective C

Yes, just as Flash/ActionScript. At a time, we almost believed Flash Player was everyone on the Internet.

Isn't ActionScript just a dialect of EcmaScript? I would guess transitioning from that to Javascript would be pretty easy.

Without the nice IDE experience though.

Well, the Flash IDE itself was a horrible compiler for those who write mostly ActionScript. We used to compile with few open source compilers. I have forgotten the names.

There was an IDE for ActionScript called FDT built on top of Eclipse.

I meant that JavaScript/HTML/CSS has yet to offer anything similar to the Flash development experience.

It still is, https://www.leaningtech.com/pages/cheerpxflash.html

Seems like it’s going to be many years before Objective-C is no longer viable, and there’s a lot of it to maintain (especially Apple’s). I think the only Swift-exclusive frameworks are SwiftUI, Combine, and WidgetKit.

It would be pretty crazy to learn only objective c today, unless you want to go after the legacy market specifically, like someone learning Cobol to get bank contracts.

Maybe it suits some people but for most people it’s sad and frustrating to work with old messy systems in obsolete languages when there’s a shiny new one that’s objectively much better in almost every way.

Here is a little secret, while Swift is the future of systems programming on Apple platforms, there is still plenty of stuff written in a mix of C++ and Objective-C.

In which languages do you think Core Audio and Metal are written on?

To the commenter's point though, Swift is the relatively easy part. UIKit throws you into the deep end right away, it descends from AppKit from native Mac app development and doesn't try to progressively disclose complexity like SwiftUI.