As far as I have heard there are not any plans for large broad-scale rewrites of the code to take advantage of multiple cores. Such improvements are likely years away if they can be done at all. Some places in the software must simple be calculated in a serial manner due to the nature of what they are; like rebuilds of the feature tree as you cannot often cannot build things out of order without building the wrong geometry. SOLIDWORKS is still very much a CPU clockspeed bound program and you would still want to focus your efforts on having the fastest clock speed that you can get and ignore the number of cores for the foreseeable future.
SOLIDWORKS does not support SLI so there is no point right now in getting two graphics cards to run SOLIDWORKS on a machine. If you are going to put two GPUs into your system one is going to sit idle while you work in SOLIDWORKS (unless you give it something else to do). The GeForce GTX 1080 fails certification for SOLIDWORKS at large and, while powerful, may cause other issues that could be summed up as being a "Ghost in the Machine". The GeForce GTX 1080 does offer some capability for GPU rendering in SOLIDWORKS Visualize but apparently not that much better than the GeForce GTX 1070 as noted here (SOLIDWORKS Visualize 2017 GeForce GPU Performance Comparison). So, there really isn't a huge benefit to the GeForce GTX 1080 even there. If you are going to pick only one GPU though go with the Quadro M4000. If you have spare money and want to double the machine as a gaming computer then stick a GeForce GTX 1080 in too.
For the hard drives, I have read conflicting reports on how effective the new PCI/e SSDs are over SATA SSDs so I really couldn't weigh in on that.
I hope some of this helps.