The Legacy comics were plotted, long before the announcement of the sequel trilogy, so Maybe Ania is meant to replace Cade?
Cade will be appearing in the new Legacy
series, but not right away, according to the new writer/artist. It'll take place following the events in Legacy War
It's best to think of the original series with Cade as "Book 1" and the new one with Ania as "Book 2," IMO.