In the first snapshot for MoM, Mojang made zombies, husks, zombified piglins, and piglins able to spawn with spears. Zombies can now spawn with zombie horses, so that checks out, but what about the rest? Well, I think Mojang might make husks ride camels (or even better, zombie camels), piglins ride hoglins, and zombified piglins ride zoglins. That way, zoglins could finally spawn naturally too.