User blog comment:CoolJazzman/Soken Ishida death caused by Yhwach?/@comment-4800978-20130625135755

The Vandenreich were going through some policy changes which included the Quincy Pensioner benefits scheme. Feeling as though their resources could be better spent in renovating Harribel's future rape dungeon, Yhwach proceeded to steal the power of all elderly Quincy men (with the exception of loyalists like Commissioner Gordon).

And so Soken met his end at the hands of some plot-irrelevant Hollows who weren't even worth naming, unlike Fishbone D or even Hexapodus. No wonder Uryu has such angst over his family's history.