What is needed is a common "building block" language for many interesting environments, teaching higher levels of abstraction.

One language, many environments -- exactly. People remember by repeating, so completing 10 levels is not enough, but completing 1000 levels in the same environment would be boring.

You can practice the same concept, e.g. a while-loop, by letting a robot walk towards the wall, or cooking the cake until it is ready. You can practice a for-loop by collecting 3 apples in the garden or walking 3 blocks away on the map of the town. All you need is different environments with different sets of primitives and one editor with environment-independent commands.