I doubt the Mac Mini will ever see dedicated graphics ever again; it's just not aimed at high end GPU use.
That said though, in the mobile/compact space integrated graphics are getting very competitive; chances are the high end Mac Minis will be getting Iris Pro graphics either as standard or as an option, and the 128mb Crystalwell cache does a good job of closing the gap in memory performance vs a dedicated chunk of GDDR memory, the actual GPU is good too, and set to get better with Broadwell which are probably what the Mac Minis are waiting for right now.
So I guess it depends how much GPU power you really need; I'm currently on a NVidia 8800GT on my 2008 Mac Pro, but the Iris Pro GPU will outperform it on most real-world tasks thanks to more powerful shader support, more modern features etc. The dedicated card in that case only really wins if I need maximum memory transfer speeds. While newer dedicated GPUs are of course miles ahead of my 8800GT, if you're not into high end gaming or heavy video processing, then the Iris Pro should be plenty IMO.
On the other hand, if GPU performance is a big concern for you, then is it for gaming? If so, then you may be better off sticking with the cheaper Mac Mini with graphics that are good enough for desktop use, and investing the money you save by not getting a Macbook Pro, and spending that on an actual gaming machine, as you can easily build one that will outperform the Macbook Pro (it is a laptop after all).