The Nigeria international's current deal with the Blues will expire next summer.
"There was absolutely no doubt that Frank wouldn't go out there and succeed," Mikel told Goal.
"I am happy that he is back to his best, doing what he loves to do and, one day, who knows, I may go over there and play with him, or play against him.
"The first few months or so, it was a bad period for him and he didn't have the best period out there. They started raising questions here and there about his fitness and what he actually came to do in America.
"I think we, here [at Chelsea], knew he wasn't fully fit then, but once he became fit, we can see a different Frank Lampard, the Lampard we know, scoring goals and helping the team. I think Frank will never stop scoring goals. I think when he is asleep he is still scoring goals."