If that brief newspaper announcement of recent changes in the Republic National Bank power structure seemed like the tip of an iceberg, that’s because it was. Those who read between the lines probably noticed that Jim Keay, formerly chairman of the bank and vice chairman of the Republic of Texas Corporation, has traded two titles for one. He’s now just vice chairman of the holding company. And it is significant that Keay will report to James D. Berry, chairman and CEO of the holding company, a man with whom Keay has for years had what bank insiders call “friendly conflicts.” Primary significance of the musical chairs is this: Former Republic chairman Jim Aston, at 68, is finally phasing himself out and wants it known both inside and outside the bank that Berry is the undisputed number one man. Insiders say the real contest between Berry and Keay came to an end two years ago when Berry was named holding company chairman instead of Keay. This move is simply intended to remove all doubts of Berry’s supremacy. But Keay doesn’t exactly come out a loser in the shakeup. Republic of Texas, which now owns 20 banks, wants to own 40 by the end of the year to become the largest bank holding company in town. Keay will be a central figure in that buying spree. (The board is not exactly disappointed that under Keay’s chairmanship, the flagship bank of the chain moved into a $l-billion-per-year growth rate.) As a further sign that Aston is serious about turning over the reins to Berry, look for Republic to adopt its first mandatory retirement guidelines at the annual meeting in April.