7,1 will have a 6 core entry level CPU with custom Pirate Islands GPUs. This will probably be out in Spring- Summer '15.
This is unlikely since the cost of the v3 Quad and Hex core CPUs hasn't changed. You're suggesting that Apple will either take a hit on margin or raise the price of the entry level. Neither is likely in my opinion. Hence (assuming Apple does a refresh to Haswell for the nMP) the 7,1 will likely start with a Quad core at the entry level.
An interesting fact is that although the top CPU's have gone from 6 to 12 and now 18 cores, the entry level over the last 6 years has been a quad core.
8, 1 will move to 8 core entry level at the end of 2016. That is when the entry level system will match the best CPU performance of the 5,1.
This is the iteration (Broadwell) that we might see a Hex core in the entry level. I can't see an 8-core becoming the entry level CPU for some time.
It's going to be interesting to see how Apple will react to Nvidia's new connector for Pascal GPU architecture. If they adopt it they will have to redesign the trash can again because they will have to move the SSD from that piggy back position it currently occupies on the back of the graphics card, unless Apple finds a way to stick a PCIE port on the back of a Pascal.
First off, we don't know if Apple cares at all about Nvidia. So far they seem perfectly happy using AMD. However, whether Apple uses Nvidia or AMD GPUS they are designing their own custom cards so it's pretty easy for them to add an SSD connector to either. And if you're referring to NVLINK, then Apple will either jump in with both feet on that if they adopt Nvidia, or more likely, it will be one more reason Apple sticks with AMD.