So this technically IS the continuation of it - the Drifters and the Trigs have a very intertwined
story. I’d like to point out that this is “Invasion: Chapter 1” . I’d be surprised if Chapter 2 isn’t focused on more than just the Triglavian Collective 
As for ships from them, yeah I definitely hope for the same - certainly hoping they end up somewhere similar to my old thread on a hypothetical Drifter precursor shipline~