I love the idea of typed base language to implement a higher level more flexible language while still being able to drop down for correctness and speed. Gradually dynamically typed, ;)
Another thing to look at is https://chocopy.org/ a typed subset of Python for teaching compilers courses. Might be worthwhile pinging Chocopy students and enticing them towards epython.
What is the semantic union and intersection between EPython and Chocopy?
I think the approach where a typed subset of Python is used to compile a fast extension module is the way forward for Python. This would leave us with a slow but dynamic high-level-variant (CPython) and typed lower-level-variant (EPython, mypyc & co) to compile performant extension modules, which you can easily import into your CPython code.
The most prominent of such projects I know of is mypyc [0], which is already used to improve performance for mypy itself and the black [1] code formatter. I think it would be interesting to see how EPython compares to mypyc.