iirc, it was stated that in the past the community had found a way of figuring out where populations migrate to. I’ve already seen guild advertisements getting ready for Classic which is a good way to do it, that way when realms are listed it can be decided upon for the that guild.
He said that VAS will not be available right away but maybe a year from now or something they would look into it again.
Information was found in: Interview with Ion Hazzikostas