In June 2014, Millar confirmed that the plans for Kick-Ass 3 will indeed move forward as the fan base is strong enough for interest to be sustained. In August 2014, Millar confirmed that the plan has always been to make three films based off the three books. In August 2014, Millar said a third film is still up in the air and that it's ultimately Matthew Vaughn's decision as he has the film rights.
Millar
Matthew Vaughn