I've posted this before, I'll say it again.
There won't be a new Mini this year.
Apple still has not introduced the new Mac Pro yet, and any revamp of the Mini will come _after_ the Mac Pro has hit the market and is selling.
Apple will not let the Mini steal from Mac Pro sales or impact them if possible. The best way to assure this is to hold back the Mini introduction to let the Mac Pro shine on its own.
I would expect to see a new Mini (that is, if there's going to _be_ a new Mini) up for sale in January or February 2014.
Maybe December, but again, ONLY after the Mac Pro is on the shelves...