My theory is that they are..... More Elephants along the lines of Zunisha. In Mythology, it is four elephants, standing on the back of a Turtle, holding up the World.
This leads me to believe that it's been a pair of four the entire time. However, due to something Zunisha did in the past, she's been forced to walk the Earth alone for 1000 years as a punishment.
The popular theory is that Wano itself sits atop the back of a giant turtle. So if now truly is the promised time, and Dawn is meant to be brought to Wano, then Zunisha herself is walking towards Wano, as well as the other three Elephants from Thriller Bark. That way by arcs end, we'll have all four elephants, descending upon Wano (A Giant Turtle) which will be the beginning of a the Dawn of a New World. All Four Elephants, on the back of a Giant Turtle, meant to symbolize, holding up the New World that will soon be brought about.