There was just a refresh of CPUs (+200Mhz) with no 800M upgrade even though those are widely available for months now. Looks like they might drop the dGPU altogether. The only reason I see why not to include the 800M is so Broadwell by itself compares well to the 750M. If they put in an 850M Broadwell only would be a downgrade with more complaints.
Nvidia more or less uses the mature last gen for its big mobile GPUs usually like the 970M-980M. Those will likely be 28nm. While the 960M and lower will be the 20nm Maxwell and likely still be a few months out. 840-860M is still 28nm Maxwell.
There is methode to Nvidia's madness. They basically will keep the 970M/980M around as the highend options while later on probably along with braodwell releasing the more power efficient 20nm 940M-960M. So the high end buyers always think they got the newest stuff and not wait for a 980M while nvidia isn't willing to put a big 20nm chip into production on 20nm.
They have done similar in the past. It seems wonky but that is/has been basically how they always do it.
Still despite Maxwell being really good and probably still better at 20nm and well ahead of even Intel Broadwell, I have my suspicion that 800M not showing in this refresh means Apple will take the Intel GPUs are good enough now approach. In all honesty they are. Except for gamers and/or very few people that are better served at getting notebooks like the Dell Precision M3800 those dGPUs are dead weight that just need lots of space on the logicboard.
Don't forget with Broadwell the logicboard can shrink two fold because the Intel chips will go down from two to one like in the 13" notebooks. Removing the dGPU as well makes for quite a lot smaller logicboard.
