Even though Ant-Man did well, I doubt there'll be a sequel for him. I see him working in the cast, along with Wasp, in The Avengers films, just no more solo stuff, I'd say.
I personally think a Wasp film with Ant-Man tagging along could be cool. But how do you not make it a retread of Ant-Man? How to entertain the audience with a shrinking hero again? Entertain those that loved it yet still felt it was a Iron Man-esque character and setup? I get a new story and a new villain will be peoples' answers, but me thinks audiences are just too superficial. Then again, superficiality gets butts in seats. I dunno. I just didn't feel the love for Ant-Man from the public like I did with other Marvel flicks. Seemed like many didn't go to see it. Which box-office says they didn't.