Not only did they guess it should be updated; they even left plenty of mechanisms directly in the constitution that allowed for it to be updated radically whenever situations changed so drastically that a supermajority agrees that it should be changed.
Unfortunately that too is the downfall; as those who want to exploit the status quo are also empowered to leverage their money and power to prevent such a majority from taking place. The constitution is far from perfect, and it absolutely should’ve been amended many hundreds of times over, not just the paltry less than 30 times we’ve managed to do so already.