According to Robert Downey, Jr. Iron Man 4 is happening and truth be told I am a little torn by the decision. It’s a good thing because Downey, for millions of people (including this writer) embodies Tony Stark.
It’s not such a good thing because Marvel has to know that they’re just delaying the inevitable. Originally when this question was posed to Kevin Feige, President of Marvel Studios, he said something to the effect that the plan was to have the Iron Man franchise to be similar to James Bond, in that the actor who plays Bond is important, but less so than the franchise itself.
In other words, the actor who plays Iron Man would change from time to time.
The thing is that Marvel Studios is known for their thriftiness (or miserliness, depending upon how you look at such things) and it goes without saying that they must be paying Downey a butt-load of money, to put on the red and gold suit again (though in Marvel and Feige’s defense, Iron Man 3 made over $1.2 billion on a $200 million budget, so $50 million–what he earned for Iron Man 3–was just a drop in the bucket).