Isn't this what Google Groups is used for? (what's different / lacking there? I'm of the age where I remember SourceForge as somewhere I would sometimes download things from as a young teenager but nothing more than that)
Yes, Google Groups is very close to what's needed - unfortunately, it's proprietary and Google doesn't really maintain it, it's only a matter of time it goes the way of Reader.
FWIW, Google Groups powers email distribution lists for Gmail for Work. Or at least, the two are strongly linked.
At this point, unlike Reader, there's real cash behind the functionality. It's possible they could just fold it into Gmail, I guess, but with other mail interfaces like Inbox popping up in the Google ecosystem it seems if anything they're trying not to shoehorn too much more into a flagship product.
My guess is Groups will stick around for a while yet.
As someone using Gmail for Work: This is one of the things I absolutely detest about Gmail for Work. The Groups interface is absolutely horrendous, and we don't want groups, we want simple email distribution lists.
Also, Groups doesn't have the ability to import archives from my previous list. (I'm in exactly the same position of wanting to migrate away from SourceForge, and the mailing list is the last thing remaining.)
