They could have rushed Ant-Man, but Edgar Wright wanted to finish his "Cornetto" trilogy before his creative partner died of cancer. (Shaun of the Dead, Hot Fuzz, At World's End)
His creative partner is now in full remission (from what I had read a while back) but he didn't know it would turn out way that 2 years ago when he put The Worlds End into full on production mode to be completed asap.
Wright & Whedon sat down and tweaked the original script to fit better with the still uncompleted at the time Avengers 2 script, so it's still possible that Pym created Ultron, but Stark brought him to life.
and such good things may come if Fox lets that F4 IP slip past it's Oct production date.
They really should just focus on branching out all the X stuff.
X-Men, X-force, Deadpool, Wolvering, X-Factor, Project X, X-Men Origins: Magneto/Storm/Cyclops and last but not least - Maddox: The Multiple Man
That is already so much for one studio to focus on, they should just do that.
Would make for perfect timing of tying in the cosmic Marvel back to earth with Reed & Company having been in space when something happened at the end of GotG or A2.
I really shouldn't get my hopes up though.