I am still personally wondering/hoping that when the Man in the Mask is revealed, we will find that we've been dealing with Hunter Zolomon impersonating The Flash for so long that even Well's was fooled (or in on the whole thing because of Jessie, but it would be weird that he hasn't mentioned it yet, so its unlikely), and that no one knows the real appearance of the Earth 2 Flash, and the big reveal will be that Jay Garrick is played by John Wesley Shipp.^Yeah, granted. And The Old Mixer's right that the ring seems to be in the Fortress of Solitude's display stand rather than on a hand as I'd thought.
So if the Legion ring has no future relevance to the Arrowverse and was just an Easter egg, that may increase the chances that the glimpse of the '90 Flash was just an Easter egg rather than a clue to an upcoming storyline.
I'm actually expecting two sets of twins, however. But technically, all that has been really proven is that Zoom pointed out his Earth 1 doppleganger on the bench. Jay Garrick could still be anyone, with the twin story a cover for Zoom.