I was thinking of writing the core in C++ (or even Haskell - I just realised that I haven't even considered it!) and using Python as the main scripting language, sorta like it is in Blender.
I just read through what you had to say about the death of HyperCard.
Why do you think Python etc. do not fill the hole HyperCard has left? Is it because of their ever-so-slight price of admission (which tends to push non-professional users away, as compared to the comfortable familiarity of a GUI)?