No, this is NOT news that former Batman, Adam West, will be appearing/voicing anything in Batman 3. Relax. This is news that that West may be voicing Bruce Wayne's father, Thomas, in the Cartoon Network animated series, Batman: The Brave and the Bold.
The rumor comes from Collider, where they have a quote from one member of The Brave and the Bold's creative team (who Collider is keeping unnamed for now) who hints that West will be voicing Thomas Wayne on the show's next season. Here's the quote:
"Julie Newmar is playing Martha Wayne, and playing Bruce's father, Thomas Wayne, will be Adam West! I think they're very appropriate parents for Batman... I should probably not be revealing this."
The episode West will allegedly lend his voice is said to take its story from some of the original Batman comics (specifically mentioned is the miniseries "The Untold Legend of Batman"). It introduced the notion that Batman's father actually wore the bat costume before he did, fighting mobsters in the bat suit while at a costume party.
It seems almost fitting that West would lend his voice to The Brave and the Bold, considering the cartoon series is often compared to the original '60s TV series (in terms of lightheartedness, that is) where West portrayed Batman himself. West has voiced several different roles in various Batman short films and cartoons, but, now being an older gentleman, it seems really appropriate (and humorous) that he'd voice Batman's father.
If this rumor turns out to be true, what would you think about Adam West voicing Batman's dad?