User blog comment:Xilinoc/Ch. 629 - Gate of the Sun/@comment-26091912-20150604121151/@comment-24726378-20150604212741

Always thought the last one would be uryu. Much like aizen, ichigo, and kenpachi, yhwach has shown great interest in Uryu because he has powers that yhwach can't see. Also explains why he made him his successor.