[mothered]

What I meant by reply is, (last post being the original or when any user last commented).

situations in which a thread needs to be open for more than a year with no replies

Your post Is quite clear, and I've answered It accordingly.

What's the likelihood that these users are still looking for an answer a year past? 

I can't answer that, nor can anyone other than the OP, hence threads are evaluated on a case-by-case basis.

I'm not opposing your suggestion, but rather stating that threads cannot be closed purely based on their age, and without taking their content Into consideration.