If the technology continues to improve, we may one day get an Ant-Man and The Wasp prequel focusing on Hank and Janet, which is something Douglas recently expressed interest in pursuing at some point in the future.
Given the fact that Janet van Dyne will appear in flashback sequences in Ant-Man and The Wasp, it seems reasonable to assume that Hank Pym will once again find himself de-aged on the big screen as well alongside his wife.
Marvel has become exceedingly good at using this technology to age or de-age actors (it has been used in everything from Captain America: The Winter Soldier to Captain America: Civil War to Guardians of the Galaxy Vol. 2), and the use of it on Michael Douglas and Michelle Pfeiffer is the next stage in its evolution.