I'm still exploring the EDZ while past the soft cap, but all of the lost sectors in Trosland (Widow's Walk, Atrium, and Terminus East) still reward blue engrams. I have a 1588 gear score and they've all dropped blue engrams for me.
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Just an update on this: This is the first time I've completed these lost sectors on my Warlock. I've rerun these lost sectors listed above and I haven't gotten blues. It may be that upon the first completion of a lost sector on a character automatically gives a blue engram without checking to see if the player is above the soft cap.