<p>Personally I prefer your option 1 relying on existing SE machinery.  As a user in search of any SE answer, you should look at both the date of the question and answer.  A 10 year old question/answer may be out of date, so the onus is on the user to find the answer that is most relevant.  A newer answer that is better/more relevant can make its way toward the top and positive comments on the quality of the new answer can guide users to its accuracy.</p>
<p>I've responded to old popular questions that had high-rated original accepted answers, and I've seen my new answer slowly march its way toward the top over years.  The new/better answer may never be accepted ('tis the case with all good answers), but a combination of submission dates, votes, and comments should be sufficient to guide users to the most timely answer.</p>
<p>I also don't have an issue with your solution 2, so long as sufficient time has passed between original question and new question (AT LEAST 5 years perhaps?).</p>
