Digging through internal codes of the latest version of OS X El Capitan, the Pike’s Universum discovered references to a possible new model of Mac Pro identified as AAPLJ951.1 (the current one is AAPLJ901.1).
Given the similarity of the codes, it is quite possible that we are now talking about a MacPro7,1 – an evolution of MacPro6,1 released in late 2013. There is no concrete rumor yet about it, but it is quite possible that this is a general update of internal components (including new generation Intel Xeon chips Broadwell) without external visual changes.
A curious part of the codes found is that they indicate the presence of ten (!) USB 3.0 ports, while the current model has only four. But honestly, I very much doubt that we see this happening in practice.
There’s still time for this new Mac Pro to come out this year – or, who knows, in the beginning of 2016…