Everyone familiar with Marvel comics knows that it was originally Hank Pym who created murder-robot Ultron and not Tony Stark. The thing is, Ant-Man and the Wasp could have introduced a feature in the new Ant-Man suit that could have harkened to Ultron.
Check out this concept art:
MCU concept artist Andy Park also had this to say about the concept (via ScreenRant):
"Peyton [Reed] wanted to explore a helmet that could expose Scott's face but still be protective… I came up with the idea that the helmet could have two modes: a normal mode with his helmet closed as we know it, and an alternate mode that had a transparent red blast shield come down after the front part of the helmet raised up to expose his face."
If you look at the design for the helmet on the top left, you'll notice that the red eyes and ‘mouth' look very reminiscent of Ultron. I don't know if this was done on purpose, but if it wasn't then that would have been a cool coincidence.
Though Age of Ultron ended up being a passable Marvel film, a lot of people agree that James Spader's Ultron was pretty fun to watch. Though he may have been offed by Vision, I'm still holding out that he could come back in some way. Maybe they could even have him as a villain in Ant-Man 3?
Ultron may be gone, but you can still check out Ant-Man and the Wasp now in theaters.
See Also: Avengers: There's a Neat Ultron Easter Egg Hidden in Vision's Design