1. Database, which forms all the MO content, should be changed in a way that any posting, altering, deletion, interface change, etc. deletes nothing from the database, but just adds more entries. This is acute, if not already in place.

2. User interface to MO pages should be changed so that it includes something like a "[mini way back machine][1]" element. Uncovering and fiddling with this visual element should bring the visual state of the page to that of the time selected. This could be done in short/midterm.

3. A separate visual element could show the historical status of the page. For example, "locked in 1970's", "new", "building up during decades/centuries", "activity dying up", "claims backing up/recent deletion" so that a visitor can be informed if much/anything can be gained from looking in the past. This is not acute and could be implemented over time. This visual element should make visitors aware if there have been major refubrications of the page content. 

4. There could be a special string added to [URI][2] of string that forms the web adress in the way the http get method works. For example, mathoverflow.org/example-page?date=20140207&other=value could be direct link to a the page mathoverflow.org/example-page?other=value as seen on February 7th, 2014.

5. Citations could follow the format proposed by Emilio Pisanty in a comment made on February 2nd at 21:25, to the another answer of this question, or be supplemented with the URI from my point no. 4.

6. Scholars following a citation to MO should be aware how MO works. This awareness will be built over time, so that following a decades old citation would be dealt appropriately by researchers, say 20-50 years in the future.

7. Archiving as done now, which is public database dump + free current MO source code, would stay enough, in case of a catastrophe.


  [1]: http://web.archive.org/web/20140110111454/http://mathoverflow.net/
  [2]: http://en.wikipedia.org/wiki/URI_scheme