The only reason I'm posting about this is to clear this rumor up. Yesterday, E! Online posted that they had an interview with Josh Duhamel and he said that no one is returning. Now, all across the internet, sites are claiming that the TF3 cast will not be involved in TF4. I'm surprised that even TFW2005 is claiming this as well. Let's analyze what Duhamel said, shall we?
"I don't think anybody's doing it, I know Shia [LaBoeuf]'s not doing it. I
don't think Tyrese [Gibson] or Rosie [Huntington-Whiteley] or anybody else is doing
So here Josh says "I don't think". He does not say no one is doing it. Now we know that there is a high chance that Shia will not be returning, but Tyrese and Rosie have expressed interest in coming back.
"I haven't heard anything about it. They haven't called me."
This statement is what really makes me not worry. Pretty much all he is saying is that no one contacted him yet. Michael Bay is not concerned about Transformers right now and there is no story yet. If there is no story, than how can they start hiring actors yet? Plus, TF4 was probably not going to be announced for quite some time, but one of the producers (Lorenzo di B.) spilled the beans on it. So please, do not take this rumor seriously at all. We will probably not hear about casting until late this year.