I really don’t see gcc support is itself holding us back. At least not more than the incomplete CoreFoundation, or the fact that base is not build on top of core base,
Or GUI on top of Core Graphics which would then have its backends... but that’s too deep of a rabbit hole :(
the binary incompatible of Foundation and GNUstep base or the missing usage of C++ in the implementation of GNUstep.
Now, I see what David says about use of C++ in implementation of Foundation... but I’d expect that putting C++ would bring the compilation times up for everyone. Not a showstopper, but there’s something cool about all of GNUstep being buildable really quickly (configure steps usually taking longer than the build of the project itself).