I have given up on guessing what Apple will do with the Mac Pro.
The design Apple made, using Ivy Bridge-EP CPUs and "Tahiti" class AMD GPUs, could trivially have been updated to Haswell-EP and "Hawaii" class AMD GPUs... about two years ago. When I say "trivially", I really mean that. Intel maintains platform compatibility for three generations on its server chips, and the new GPUs were the "1.1" update from the same manufacturer, with the same TDP and other characteristics. Apple could have slotted them in, and could even have kept the old variants around as lower end models. Apple didn't.
So what now? There "Broadwell-EP", the next generation on the same platform, which has been out for a few months by now. There is the AMD "Fiji" GPUs, which are memory limited but otherwise fine, but they're getting old - or Apple could switch to nVidia, if they're friends again. OTOH, the next Intel CPU, "Skylake-EP" and the next GPU of the same design "Vega 10" won't be out for a few months more - both on newer platforms that would require a bigger redesign.
So really they could go either way. The fact that Apple didn't make an MP update two years ago makes me think that they might have given up on the MP, but then they have also left the Mac mini to rot, and the MBP is very long in the tooth now.