So what about the last 300 years was unforeseeable in your view? Leonardo Da Vinci foresaw flying vehicles, cars, robots, massive population explosion, medical advancements, war machines, tanks, and a myriad of other things centuries before the founders were around.
All of the founding fathers were well read and familiar with history, philosophy, warfare and technologic advancement principals. Many were renaissance men in their own right, inventors and scholars. They might be amazed at computers and information tech from now but I doubt they didn't think about multi-shot weapons. Many of them had pepper boxes and other multi-shot weapons at the time and in their lifetimes they saw massive military weapons innovation as well as the invention of the printing press and the beginnings of the industrial revolution in Europe, (though it did take 50 years more to get in full swing in the US)
I always wonder when people say the founding fathers couldn't foresee the modern world. People hundreds of years before them saw a lot of what we have in the modern world, why act as if they were incapable of seeing where at least some advancements would come in. If anything, war and communications advancements were the most obvious areas to figure out.
So maybe they couldn't foresee the rise of internet news outlets like CNN and MSNBC or something like a Facebook and Amazon but they understood the press and commerce very well and it's not a stretch to say the ideas they had way back then can be applied to new media and internet commerce without a whole lot of "interperetation" needed.
There might be some specific instances that the founders were unaware of as a potential issue or maybe just didn't bother to expand on, like same sex marriage but even that is not too tough to figure out from a constitutional standpoint. It's listed no where that the federal government has any authority over any marriage. Authority falls to the state unless the people of the state got it passed into law that the state has no authority over it or the state simply has no inclination to create law around it. If multiple states have conflicting laws, the Federal government and Judicial system have tools to deal with that, though to date no one seems inclined to really solve that particular issue but it's not because they don't have the tools or guidance to do so, it's politics stopping it.
So again, the SC must take the Constitution and apply it to modern situations but there's very little that requires "interpretation", just a determination of what parts apply to the case in front of them and exactly how. If no parts do then it's simply not a federal case unless it is a conflict between the states of something they don't have federal authority over or something regarding foreign entities. I remember reading something like half the SCs workload is working with the Native American tribes with issues in conflict with the US.
Some more thoughts...
-Jim