Michael Bay gave Josh Duhamel a call to congratulate him on the news that he and his wife, Fergie would be having a baby. Bay also had some news for him as well. He wants him back as William Lennox in Transformers 4. Duhamel will be the second human character to return from the previous trilogy, alongside Glenn Morshower. He could end up returning for just a cameo but I'm not ruling out a complete return either.
"[Michael] said he wants to put me in it someplace. I don’t know if he was just saying that because he had me on the phone and he felt obligated or what, but you know what? I got to do three of those. It changed my career, it changed my life getting to be a part of something that big, so I’m grateful for even doing the first three of them."
Source: The Hollywood Reporter