Exactly as you say, everything is currently up in the air as to whether the next DA is given or not. Any additional Short HST Sets will either have to come from the Angel Trains stable (Most of the Power Cars are in Ely, some Power Cars and Trailers are in Laira after being stood down after Christmas) or Porterbrook (Nearly all are in Long Marston). However, I'd expect more trailers to be heading down if the DA3 is given after First Rail Holdings purchase of the Porterbrook 4 last year.
Yesterdays move consisted of all Porterbrook vehicles including 3 x TGS, 3 x TS-D, 2 x TS, 1 x TF in the order of 43196 / 41167 / 44068 / 42302 / 44042 / 44069 / 42310 / 42231 / 42094 / 42103 / 43071.