Not a new rumor, but updated and expanded. The rumor previously was Jason Todd would be an important plot element. Harley and Joker are supposed to be on a split as there will be a reference to killing Jason Todd in the movie. He may not appear in the movie, but the inclusion of his death is a major plot point.
From Comic Alliance:
The latest rumor has Batman’s former sidekick Jason Todd (aka Red Hood) featured as somewhat of an important plot element. But the more exciting news is that WB has their eye on the directing duo behind John Wick to helm an upcoming movie in their DCU.
a previous rumor about the Suicide Squad plot explained that the Joker’s past crimes would be referenced, including how he murdered one of Batman’s sidekicks. It was more than fair to speculate that the sidekick in question would be Jason Todd, one of a few characters to don the Robin costume. It seems as though that speculation was correct according to the latest rumor.
In addition, Umberto Gonzalez from Latino review had this up on Instagram:
Jason Todd’s uniform is in a display case inside the Batcave! In fact, The Joker & Harley Quinn are estranged in SUICIDE SQUAD because she feels guilt over the death of Todd. I’m also told that the RED HOOD is now a priority character for DC. One more thing, John Wick directors Chad Stahelski & David Leith being courted to direct DC film!
So Red Hood has become a priority and will appear in future DC movies.
Time to look at the spec:
First appearance of Jason Todd is Batman #357
Jason Todd’s first appearance as Robin is in Batman #368
First Post Crisis Jason Todd is Batman #408
Jason Todd’s death takes place in Batman #427 and Batman #428
First Jason as Red Hood is Batman #635