This is something I've thought of, as someone who was quite into GC2, and spent a great deal of time on that site.
The old GC2 site had a "library" tab, in which users could upload mods. This made it quite easy to find them "all under one roof" as it were. Will GC3 have something similar?
GC3 does support steam, and presumably steam workshop, but personally I find just getting the mod in a zip file far more useful than going through another service.
I ask, because currently the only solution used so far seems to be dropbox.