In addition to not interacting with the GNU toolchain at all (through MinGW), MSVC support will indeed enable native Windows debug info (as you mentioned) so native tools can be used to debug Rust code. Note that this isn't 100% implemented yet, but it's coming soon! Additionally you'll get interoperation with MSVC-compiled libraries. Libraries compiled with MinGW don't interoperate well with MSVC (and vice versa), so this enables Rust code to link against an MSVC-compiled native library.

(HN readers, note that alexcrichton is the one spearheading the MSVC effort.)

Will MinGW still be supported, or will that be dropped?

There's no plan to drop it.

https://github.com/rust-lang/rust/pull/25350 was the PR with the initial support.

    > The tl;dr; of this change is that there is a new target of the compiler,
    > x86_64-pc-windows-msvc, which will not interact with the MinGW toolchain at
    > all and will instead use link.exe to assemble output artifacts.

We're very interested in improving support so that you can use VS's features fully. These are just first steps.

MSVC support primarily means that Rust programs link with the MSVC toolchain, and use structured exception handling for unwinding. There are no GNU components involved and no need to install MinGW.