[dawnofdusk]

>FWIW our CS program mandated a programming languages class and the first third of the class was taught in Scheme.

This is important but doesn't replace having a dual-track intro sequence. The reason one has "physics for physics majors" isn't because physics majors need to learn some of this complicated stuff ASAP. They definitely don't, and I don't doubt students in the program will eventually get a well-rounded education. But it's a good idea to give incoming students a taste of what the field is like as soon as possible, so they can see if they like it or not. (Essentially it's a "weeder", but for the students' sake so they can self-select on interest and not just instructional staff's sake of being elitist.) Probably some (but not all) professors/postdocs/grad students would scramble to teach the more advanced sequence as it is likely more engaging for them than the current intro curriculum.

To be clear I don't think an advanced intro CS can't be in Python on principle, but such a class probably introduces multiple languages to some degree: they could be toy assembly languages or real ones in addition to the majority of the course content in Python.