As of July 5th 2015 mirrorless is not ready for prime time. But who knows what a year or two or three will bring. I have no intention of ever changing or "upgrading" to mirrorless. My next purchase in a DSLR will be a 1Dx if I buy anything. One good reason to buy the best when you do buy is, it stays viable for a longer time.
Not many, if any, cameras made today top my 1D Mk IV and 1Ds Mk III. Yeah, a few may have a better paper spec here or there but not a real world difference.
If you truly want to upgrade, get into a 1 series. You will never go back to a lesser camera. But you do as you see fit.
EB
EOS 1D, EOS 1D MK IIn, EOS 1D MK III, EOS 1Ds MK III, EOS 1D MK IV and EOS 1DX and many lenses.
