actual burrmaster here
while I do think Zima getting an alt is just a matter of time, I am not holding my breath for it to be this October's event, since it is likely the main story chapter
the main story party is heading to Chernobog while they got explicit orders to keep away from that city, they are going in with fake identities and their real names must be kept secret at all cost, going to Chernobog would be an unnecessary risk to the operation
as far as alt-ability goes, it's Zima>Rosa>Gummy>Absinthe (even though she's not a USSG member)>Istina>Leto
the reason I put Rosa second is that for some reason she's being isolated in extra material and Skade herself said that her growth and rebellion "will take some time"