Many fans have already begun to theorize that Vandal Savage exists in the DCEU based off of evidence supposedly planted in Batman v Superman (though those theories have yet to receive confirmation), so he would be a natural fit for the 1980s Wonder Woman 2 setting.
The Amazons already fulfill that role, but if the folks behind Wonder Woman 2 need a similarly immortal villain, then they should look at Vandal Savage.
The iconic DC baddie is a hyper-intelligent caveman granted knowledge and an infinite lifespan due to exposure to the radiation of a mysterious meteorite.
In a DCEU movie that is going to play with a different setting than anything that we have seen before, it behooves DC to take advantage of the characters who don’t age like normal humans.