I think the better option than long support is support stopping to give room to PZ2 down the line.Regarding support: I guess the year and a half is given and we can not count on dlcs after that, but if sales are good, I still don't think they will be impossible.
Because I don't think a lot of new core mechanics (aside aviaries) will be introduced in this iteration, and similarly to JWE/2 they could use the first installment models to give us more animals from the getgo.