I looked through a wiki list of "Old City Halls" in North America to gain some perspective on how ours could be repurposed.
Ottawa - Converted to govt office space
DC - Converted to court space
Boston - Converted to office space
Knoxville - Repurposed to a law school
Mobile - Converted to a Museum of Mobile
Bellingham - Now houses the Whatcom Museum
Richmond - Converted to office space
Tacoma - Vacant for 10 years, eventually converted to office space. Apparently the owners neglected the building and the city recently repurchased it.
Detroit - Demolished in 1961, which is a bit of a travesty.
This survey is troubled since it just looked at places called "Old City Hall," which obviously doesn't include cities whose old city halls simply weren't called "Old City Hall." Looking at major American cities that have an "old city hall" not currently in use by a municipal government, though:
Seattle - Previous city hall shared space with the local court, which took over after city hall moved.
Dallas - Various govt uses, including Police Headquarters. Seems to have been partially abandoned and is now being converted into a law school.
Phoenix - Now used for court houses (interestingly, where
Miranda v Arizona, where 'miranda rights' come from, started here).
Austin - Has a newish looking city hall, but I can't figure out what was used previously.
New Orleans (Gallier Hall) - Seems to have a mishmash of uses including a convention centre, a theatre and a reception hall.
This list is hardly exhaustive I imagine, but it's a decent sample. I think they also show how difficult it is to convert these types of buildings. Superficially, lots of them were built by ambitious municipal governments and subsequently were too expensive for most uses. The most common fates seem to be conversion to court houses and leasing to office space. Many of those converted to office space seem to have had troubled economics. I imagine they'd be much less practical than new office buildings from a tenant POV.
P.S. I did not know that
Cincinnati and
Minneapolis have nearly identical looking city halls to us! Both are still in use as municipal buildings though.