What do the new ARM macbooks mean for developers who don’t exclusively work with Apple platforms? Will they be able to run all the current OSX software like IDEs and Docker?

Yes, there's a compiler to convert x86_64 binaries to ARM ones. This is to be transparent and should not be visible to the user.
Also more software will be compiled for ARM, so this will be less a problem in the future.

With Docker I'm not so sure, but there should be some kind of emulation.

Some languages like Go have the ability to cross compile to other platform including ARM.

@Bubbles Or C. Or C++. Or Rust. Or really anything that can use LLVM.

@pxeger Sure. But not all containers. And on the Pi I can just install qemu in user mode and everything works (albeit slow). I'm not so sure for MacOS, but I'm sure that there will be a solution for it.

@Fast-Nop yeah