I firmly believe that students need to be exposed to multiple language and paradigms during their four years as a CS major. We do Scala for CS1 and CS2, but we have later required courses that require students to learn C, C++, Haskell, Assembly, and C#/Java. There are also quite a few elective courses that need/use other languages, like JavaScript for Web Apps.

I think that the key to a good CS curriculum is a solid foundation language in CS1 and CS2 followed by a more diverse set of languages in the second year that make learning new languages in the Junior and Senior year easier.

The key is that the goal isn’t languages, it is concepts. However, some concepts are much more easily explored in some languages than others. Also, some languages help students mature in their understanding of key concepts better than others, IMO.