[pier25]

Sounds plausible, but why not even release an upgrade to the outdated GPUs or the CPU?

The current 15'' rMBP is faster in single core operations...

[extra88]

As a rule, don't buy a Mac Pro when you're doing single core operations. It's often not worth the money even for multi-core, multi-core plus using the GPUs is when it's the right pick. I'm referring to choosing a Mac, not comparing Macs & PCs.