The third installment of the movie series will not be directed by the filmmaker, who was at the helm of the first two flicks that saw Downey Jr taking on the lead role alongside Gwyneth Paltrow.
Asked how it will feel without Favreau on board, Downey Jr said to MTV News: 'It is weird. I think there's always a closure to everything.
'This will all come to an end one day, and I think the thing is to just really enjoy it while you have it.'
Downey Jr added: 'He's up to great stuff with Cowboys & Aliens coming up. I just spoke to him a few weeks ago and we were quite friendly.'
The third Iron Man movie is due to hit cinemas in May 2013.