According to Jay Roach, the director of the ‘Austin Powers’ films, Mike Myers is working on a fourth installment in the Austin Powers franchise. He said, “[Mike Myers is] working on ideas for it, people are definitely talking about it and I’m all good for it. I love those characters.”
As far as the returning characters and where Myers was heading with the characters all Roach had to say was, “That’s hard to say. Somewhere you haven’t thought of.” You can see the full interview below.