A couple of days ago Hiroshi Ueda, artist of Full Metal Panic! Sigma, uploaded a draft from what appears to be the final Mecha fight between Sousuke and Leonard.
A couple of weeks ago a user of Mangafox.me also shared the scans for Chapter 81 (or 82 depending on which they choose for the final print).
|Page of the 81st Sigma Chapter "Black & White"|
With this sort of progress it should be no hurdle for Hiroshi Ueda to have Full Metal Panic! Sigma finished by 2013.
In addition Full Metal Panic! Another (Manga) volume 2 has been released about a month ago and does include the six chapters 6-11. It looks like by now they prefer the abbreviation "FP!A" so we might reconsider our current one FMPA.
|Full Metal Panic! Another Abbreviation suggestion FP!A|