Apple Inc. Mac Pro

Will we see a 2015 Mac Pro?

NO

Why do I think there will not be a NEW Mac Pro in 2015?

New is wrong

Apple is not going to launch a new Mac Pro only just over one year after the launch of 2013 (2014) Mac Pro.
I think an update to the Mac Pro range will be known as the 2015 Mac Pro - new Intel CPUs, new AMD FirePro GPUs, more RAM, more PCIe flash storage & dual-slot PCIe flash storage (one on each GPU or two on each GPU).

Mac Pro in 2016

Far more likely!