How to deal with questions with a highly voted answer (outdated) and a lowly voted answer that will only become increasingly relevant

Question

Like this one: How do I get Haml to work with Rails?

This is actually pretty common to rapidly-evolving stacks like Rails (for that question, haml-rails is considered as the current standard)

I would offer the following observations:

1. There is no point in punishing the old answer, but then:
2. There is no guarantee that the new answers will ever amass sufficient votes to be on par with the older answer, as it depends on changing trends and other factors (like a drop in popularity of the topic as compared to a previous period)

For the uninitiated, a +4 but highly relevant answer is likely to be denied the attention it deserves when there is a +70 answer dangling. So the question is, is there anything else that can be done to increase the prominence of newer answers for such questions apart from raw votes?

An idea that occurred to me is that, apart from commenting on the older answers, would it be better to have a way to flag an answer as outdated? Such a flag would have no effect on votes, but will reduce the likelihood of the popular answer appearing at the top as compared to the rest of the answers.

Another idea is to sort a group of answers that have met a certain vote threshold, say 10, (to establish notability) by descending order of their posted time.

Answer 1

Instead of introducing new flags or other means to achieve what you want, I would suggest simply using what we already have: comments.

Just leave a clear comment to the original answer with the now outdated content, stating that while originally valid the situation has changed somewhat. If you have answered the question (or if someone else has answered the question) with up-to-date information, you could even leave a link to that answer.

If the OP of the previously best answer then decides that his answer is worth to update, he could simply add a new section for the updated information. This leaves the old (possibly still valuable) content intact, while the new info is also available. And if not, users are still made aware of the new situation and the up-to-date answer slightly further down (awaiting masses of upvotes ;) ).

P.s.
Since this is a collaboratively edited Q&A it is also possible to amend the top answer with the new information you have, but that does not always seem to go over too well. Perhaps prodding the OP to include it is a better alternative.