Tbh I don't really see the point.
The death scene of BM and Kaido was like Vergo's: not explicit, but also not really that vague. Sure, there was the eruption so one can think they were shot away: even though where lol? In the sea? And have they survived the eruption even?
Anyway, let's say they did... What would be the point?
If I was a fan of them, and I kind of liked BM in WC at lest, I would really hope not: their role would be to serve as an hype tool for Akainu, BB, Kuzan, Loki, Shanks, Mihawk, etc.