And I too have been through the same dilemma with my kids. I haven't got far trying to enthuse them with the RPi - even when I got Minecraft running on it, they complained it was too slow...
There was also the huge problem of choice. We had no choice - you learned the language of the system you had. For a couple of years I struggled to choose a language to introduce my son to. A friend of mine even bought an old BBC Micro so he could teach his kids the Old Ways!
But perhaps I over-thought it. A year or so ago I made an arbitrary decision and showed my son how to run Python from the command line, and he picked it up pretty fast. But then he started complaining that he couldn't work on it when he was at school (such is their expectation of cloud ubiquity). Now he's just turned 14, and I've discovered he's developing a pretty ambitious text-based adventure game, still in Python, but using a cloud-based IDE (cannot recall the name).
So whilst I admire the project - the more the better - I think to a certain degree the tools are already there and as long as they're given the seed of interest the kids will go out and find them for themselves.