Engineering and the sciences have, to a greater degree, been spared this isolation and genetic drift because of crass commercial necessity.
Unsubstantiated bullshit. Most theoretical backbones of math and science were discovered/formalized for anything but commercial reasons.
It is clear to me that the humanities are not going to emerge from the jungle on their own. I think that the task of outreach is left to those of us who retain some connection, however tenuous, to what we laughingly call reality.
You could start with your own field(s), which are full of mediocre paper-pushers milling around other people's theory, publishing uninteresting observations which, as long as they are "logical" and "correct", are shit into a godawful paper that no one will ever care about or read. "A Novel Method for Applying a Trivial Modification of an Already-Known Algorithm to Some Type of Specific Data" could be the title of about 35% of the CS papers in existence.