Take with the biggest pinch of salt you can ever hold onto, but this is apparently the first shot of a new Duke Nukem, known as Duke Nukem: D-Day.
It comes from a Facebook page based on the series, which has a message saying " Duke Nukem doesn't stay down for long." We don't know if it's fanmade or an official page, but chances are it's the former.
In fact, it could just be a new screenshot of Forever.
Take as you will.