The details appear to have gone largely unnoticed until now, but were recently addressed on the Mustang6g.com forum. Given that they don’t come straight from Ford, these may be rather speculative, but considering the nature of the report and its investor-supplier client base, there may be truth here yet. Time will tell.
As far as motivations go for fast-tracking a new Mustang into production, the 800 pound gorilla in the corner is of course the all-new 2016 Chevrolet Camaro, which has once again set up a cat-and-mouse game of updates and redesigns with the Mustang, following its return to market in 2010.
If the news does ring true, the schedule shift would keep the sixth-generation Mustang much younger than its predecessors; the fourth-generation spanned 1994 to 2004, while the fifth-gen pony car carried 2005 to 2014. That said, remaining competitive in the market is the name of the game, and it could be that these shorter lifespans are just a sign of the high-tech times.
Again, time will tell.