By Sinead Cruise and Iain Withers LONDON (Reuters) -Investment banks are likely to see a shake-up in revenues next year, with a rebound in banking and advisory fees expected to soften a hit from a fall in trading income, Barclays’ CEO C.S. Venkatakrishnan told an investor event on Tuesday. A trading surge has helped investment banks report robust results this year and helped to offset a dire year for fees on company flotations and M&A deals amid global market turbulence. That could be set to change by the second half of next year, Barclays’ CEO said. “Trading revenue pools will probably shrink…