As the developer of Reports for HyperCard, I’m a bit familiar with HC and its usage in application development. ;) While many people did many cool things with it, it was never really a general-purpose application development tool useful for creating Macintosh applications. It was, for all intents and purposes, the platform’s version of VB.

Objective-C came about primarily due to the acquisition of NextStep, as it was the underpinnings of that OS and toolkit. (In fact, many Foundation classes today are still NSSomething.) It predates iOS by quite a few years, and gained traction when Apple started pushing Cocoa over Carbon, which in turn really only existed to make it easier to move Macintosh apps to Mac OS X.

C++ was never really a contender due to its impedence-mismatch with Objective-C, and the same for Java. You simply can’t do low-level system development with Java. C (and Objective-C) are a much better choice for working with Unix and integrating with the MACH kernel.

It’s true that there was some level of effort by people to use both, but those efforts eventually ran headlong into the fact that Apple wasn’t really interested in supporting them. (Of course, you probably could also translate “wasn’t really interested” into “simply din’t have the resources (time/money/engineers) to support multiple languages all attempting to solve the same problems)”.

Which probably brings us back to Swift. Apple is quite pleased with Swift, is busy extending it (async/await, actors), and perhaps more to the point, has based their next-generation user-interface language on it (SwiftUI).

As such, while I think you may indeed see some more functional improvements to Swift (based on pitches I’ve seen in the Swift Evolution forums) as well as some proposals for other Rust-related things like ownership, I sincerely doubt that Apple will jump ship anytime in the foreseeable future.