2) Batman
Naturally, “dark Knights fall” can only refer to Batman. If you don’t think that’s concrete enough proof, though, other references also suggest that the Caped Crusader is out there.
On the Reverse-Flash’s newspaper from the future that reappears throughout season one of The Flash, a smaller headline announces that Wayne Enterprises has completed its merger with Queen Consolidated. This is from a future after Barry has helped form the potential Justice League, so it looks like Green Arrow and Bruce Wayne are best buddies by that time.
Despite the hints at Oracle and a grown-up Robin, a common fan theory goes that the Arrowverse Batman is currently at an early part of his career where he’s still considered an urban legend. And, due to the complicated relationship between the films and TV shows, we shouldn’t expect the character to make a proper entrance any time soon.