Not a shock on Texas (no pun intended). That was an obvious move.
Roy Williams retiring is a little surprising, and yes they're a blue blood for being extremely good, among the winningest programs of the decades most the time dating back to the lists in the 30s. Won titles in different decades, different coaches, that kind of thing.
And re: UCLA and my 20s/30s comment. On the Wikipedia page for UCLA men's basketball, it lists "conference regular season champions 1921, 1922, 1923, 1925, 1926, 1927 (I had clicked off that page later and included the 30s when I shouldn't have). So looks like sports-reference has UCLA as independent during that era, while UCLA is listed in wikipedia as a member of the SCIAC from 1921-1927.