Originally, I thought that Zoom's identity HAS to be that of Henry Allen (I still hold on to that theory a little) because it would make for a good juxtaposition - Henry freed of killing Nora, but his Earth 2 counterpart is on a murder spree.
HOWEVER, I have to take into account and acknowledge that The Flash has translated its villains from the comic quite well, even sticking to their civilian names/identities from the source material. Hunter Zolomon on Earth 1 seems like a normal guy and is apparently Jay's doppelganger. Somehow though, I'm starting to think Jay isn't all he seems.
I mean he said Zoom stole his speed, that's been his story all season, but then suddenly he "confesses" that he experimented with Velocity 6 previously and that caused him to lose his speed. He now has the working Velocity 9. I knew straight away that after Barry, Cisco & Wells returned from Earth 2, just by where he was standing, I knew Jay would get stabbed by Zoom and pulled back into the breach.
Anyway, if we re-tread season 1, Reverse Flash's true identity was a mystery until he confirmed he was, in fact, Eobard Thawne - sticking to the source material. This is why I think, apart from it being a potential red herring, the revelation of Hunter Zolomon is no mere coincidence. Hunter Zolomon of Earth 2 is Zoom.
Long story short, I think the creators/showrunners are finally giving us fan service, we just don't know it yet. What I mean is that the man in the iron mask is the real Jay Garrick, but he won't be Teddy Sears - he'll be John Wesley Shipp as "Geezer Flash."