Most banks are already community owned by virtue of being largely owned by institutional investors, ie. pension funds.
The benefits of being community owned implies that the "community" takes an active part in the management of their bank. In Denmark, community owned just meant that banks gave benefits to customers that put their savings into the bank's shares, they did not generally take part in exercising diligence as owners, and the few that did, struggled to get heard while the going was good. For me, my bank is a simple service provider. To the extent I'm going to be a part owner of one, I'll delegate the responsibility to people who know better than me what they're doing, ie. my pension fund.