As one telling piece of evidence, I note that over the 1980s and the 1990s more than 4,000 new commercial bank charters were granted in the United States. Essentially all of these new banks were quite small, but were able to achieve profitability in a relatively short period of time.
This having been said, we may well see the formation of a few very large financial conglomerates, but we will almost certainly continue to see many firms, both in banking and other financial businesses, that specialize in providing a narrower range of financial products and services.