I updated the thread. If you click on the Prison Break link, it says both actors (including Wentworth) has found some time in their busy schedule to film Prison Break, which means he more than likely won't be returning to RE. He can't do three projects, especially with the filming location being in South Africa.
What I don't understand is, if Paul seriously was devoted to this franchise he would've contacted Wentworth many months ago to plan his character's return. But instead it just merely proves Paul is a "last minute" kind of guy and is probably trying his best to reunite old characters (like Ali Larter) at the last second.
Honestly I'm kind of pissed and let down as a fan. I was mad at Retribution for not explaining their disappearance now instead we don't even get his character.
-edit-
I think this film is mysterious for a reason. If you go to IMDb, they updated it to 2017. They removed the [rumored] by Ali Larter AND Wentworth Miller, while the rest of the cast is still rumored.
http://www.imdb.com/title/tt2592614/
But no where does it say Wentworth is coming back.