I'm sorry if I come off as negative or harsh, I'm not trying to be insulting, but What ? "Useless building"? This building should never be torn down, nor even considered for demolition!
City Square, should have been a retail project first, at it's entire base, Assembly Row, being a good local example of the mix, only done better.
The model isn't new, it's retail as entertainment, an even better example of the retail part/ mix would be the Grove in Los Angeles, only massed differently and built to include more mixed use.
http://www.thegrovela.com/
With City Square, they have many of those mixed use elements Housing, Office, Hotel, but the retail is just a token thought, scattered and isolated, with little to no connection with each other and only a tiny fraction of the square footage needed, for retail to be successful.
As for the church itself, that should have been the signature piece of City Square, as far as how it could have been intergraded, meaning the use, there are many examples of church re-uses, that would fit within this model, ranging from bookstores to a mixture of bars and restaurants and so on. So finding a re-use isn't the problem, it just needs to be redeveloped/merchandized in a broader context.
http://www.treehugger.com/green-arc...-church-converted-21st-century-bookstore.html
With some creative thought, they can still do this in part. it would be a retrofit and have some limitations, but it can work.