I don't think there is a need for the SO engine to do anything to help people find new posts to old questions, especially in the case where there are multiple pages of answers. If you add a good answer, to a real technical question, you likely will see it get votes slowly as time goes on, and this is what I would expect to happen, and think would be desired. However, when you add an answer to an old question with many many pages, yes its not likely it will get seen too many times, but questions that end up with pages worth of answers are not the reason SO exists. These questions happen and they're fine, but I don't think they're something to system should be optimized for whatsoever. Additionally, if you want to do this on your own, there is the "newest" tab on every question that will show the accepted answer (if there is one) followed by the answers newest to oldest.