I suppose that rumours, if Frontier had given us any, would just be "there are rumours of FSM here in the region, nobody has reported any exact systems yet". Well, here we are seven or so months after we were promised to get them, and we still don't know.
As for finding GGGs: personally, I doubt that they'll ever be common. Through the Codex, we can find at best only 42 finds of each type (what with there being that many regions), so that's not a whole lot. Moreover, the ones that have been found so far appear to be in rather run-of-the-mill systems, and not highly specific ones. Although the question remains: how many might go undiscovered now? (As far as I know, they don't have a distinct place on the FSS barcode, no?)
Or think about it this way. How many people finished DW2, and how many new GGGs were found there?