Greetings Jurgis --
I'd say the answer to only-C compsci in school, or only-Java, was the phenomenon of Code Schools, with their Bootcamps. One discovered the short cut into industry was not a compsci degree, but a crash course in exactly what you're saying: a combo of py and js.
As you know es6 is looking a lot like Python. I'm coming to js through React world wherein a recent revolution got all the developers turning their classes, a new thing, transpiled by Babel, into functions only. You could do that now, and yet preserve precious state in your Component objects. Yes, I know, that's all JS echo chamber, as seen from the outside by a classical Python player. The two worlds combine through Redux and Django, right? Learn all that in Code School, forget college, and land a job. Leave compsci to the ones wanting to support whole new languages and so on. It's a big world with room for many career tracks.
Because JS world has been such a moving target, and because textbook companies publishing to wood pulp (paper) especially fear obsolescence, tying the curriculum to a "for the ages" language has been a pretty good strategy. C isn't going anywhere, C++ either, and they both take you deep into the guts of the machine, thinking low level bits and bytes, and what better time than when you're still young in high school and wide open to all this new information. Presumably you have time to concentrate and access the equipment (not a given in many childhoods I realize, with many fighting for that privilege through adulthood).
I'm not dissing the high school approach therefore, and think the Code School alternative has been, for many, a good compromise, as in "no need for more college, time to jump into industry". PY has proved more anchoring than JS in that it hasn't morphed so radically over the years. Academia has put a lot of weight on it and it has borne the weight well. JS inspires functions as objects (passable as arguments) as much as PY does.
The door I've left open is for colleges and/or high schools to offer more tracks, a greater variety. Python has made huge inroads as everyone's "first language" in the curricula around here (less so JS, because of the reasons I mentioned -- morphing so fast). One needn't abandon the C/C++ track as if it's now obsolete. We're just not accustomed to offering so many branch points in early education. There's a bias around here towards college vs. not college bound. Anyway, long discussion and much that parallels what you're thinking, I'm thinking.
Kirby in Portland, Oregon