Iron Man 3 was kind of a love-it or hate-it movie. Some fans didn't like how out-of-the-box it was, with *SPOILERS* The Mandarin being just an actor and Tony's retirement at the end. The end credits even had to assure us that Iron Man will return to keep people from thinking the character was retired. People still seemed worried about how well it would all jive with the ret of the franchise, though. Not to worry, the cowriter of Iron Man 3 recently spoke about how it would lead into Avengers 2.
Drew Pearce was recently promoting the DVD release of the film, and was asked about negative fan reaction to the ending, as well as any Avengers: Age of Ultron connections. He said:
"We take his Arc Reactor out, but I think we also make a pretty definite statement that he is Iron Man...And although Joss isn't part of the process, he saw all the cuts of the movie, so I've got to assume he knows exactly what he wants to do with Tony in ['Avengers: Age of Ultron'] and how we've left [Tony Stark] is going to help that, not hinder it."
He was later asked about how the team dynamic would be effected by the additions of new characters Quicksilver and Scarlett Witch, he had this to say:
"The core of Avengers will still be our Avengers. There will, of course, be other characters in the mix, but I think Joss is really good at creating a family and then pulling them apart. So I suspect that the first [part] in that movie will be kicking the sh*t out of those characters to see how they cope as a group."